Thief 2/Game Mechanics and Glitches

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If a trick applies to only some versions of the game, note which ones that is.

General Movement

Straferunning: Straferunning, e.g. forwards and right, is faster than normal running. Also works under water. Testing reveals that straferunning is 20% faster than running normally, and strafewalking is 40% faster than normal walking.

Jumping: When jumping you travel at the same speed you had on the ground, so it neither speeds you up nor slows you down, except if there's ramps.

Thief games have NO air control so pushing any buttons while flying through the air doesn't do anything. This means to succeed at a difficult jump it's just aiming well and timing it well. You can do a 360 every time you've jumped for style.

Mantling: earlier (OldDark) versions of the engine did a bad job with mantling whereas the later versions (NewDark, v.1.19-) correct this behaviour, making certain new movement possible, e.g. over fences.

Lean Grab: There is a technique for leaning forwards while flying through the air to extend your effective jump+mantle/frob distance which can help clear larger gaps or just cut corners more efficiently. Normally you're not able to lean while jumping so you have to do it before you've jumped. However, if you are also holding down forwards this will instantly cancel the lean. This is the correct technique:
- Strafe run to get to full ground movement speed.
- Jump once and wait until you've landed. (This step is only useful if there's a down slope to boost off.)
- Immediately release forwards and activate forwards lean while jumping again. You should now have the maximum speed but also be leaning. If it fails, make sure you're doing the other two actions slightly before jumping.

Use forward lean to get closer to doors to be able to open them sooner. In addition, if the door is not on the side you're looking and leaning towards, you can jump right before you turn to face the door using the lean grab technique so you don't lose any ground speed while facing the door.

You can go all the way around a ladder without detaching if there's room.

Soft drop: if you drop down from a ledge while crouched, you will make no noise. This even works on tile and metal. The exception is when you take damage, Garrett will say *humpf*.

Elevatoring: you can climb up by dropping flares, scouting orbs, various food items, keys etc. on top of your head and just jumping about 3 times to get lodged inside them, then dropping another item and continuing this way. If you don't have any more left when dropping an item, it will fall right through you, so you need at least two of each kind. You can use this to perform various tricks including stopping your momentum when falling and jumping off the items that stopped you or just getting a mid-air bump from the item. The extension is you can traverse across the air by repeatedly hopping, dropping something you get caught inside, hopping and so on. The bigger the item is the easier it is to utilize for this. If you manage to keep picking up the items behind you you can travel an arbitrary distance or get as high as needed but it's very difficult not to fail.

When climbing upwards, you need to push the view up to the very very top, which is difficult to do at least in v. 1.07. You have to keep moving the mouse even after the pitching initially stops to get the last few pixels.

The easiest items to use in elevatoring are all the ones with bigger hitboxes, e.g. loaves of bread, cucumbers and scouting orbs (although those have the annoying camera shift effect). Flares are seemingly a bit more difficult to make work. It's also more difficult if you're not right next to a wall that keeps the items from sliding off on that side. You should be facing the wall when dropping them.

Alternatively, it is apparently easier to lower your mouse sensitivity first before trying to move the view all the way to the apex.

Quick Elevatoring: In this variation you just kind of spam-drop the items (the more you have the easier) above your head while also spamming jump. If you get very lucky you can get to a significant height and most significantly it happens much quicker than with slow elevatoring. This has been used to successfully scale the walls right next to the exit zone in Ambushed (using 5-6 cucumbers, apples or loaves of bread) but it's very difficult.

It is believed to be possible to do a quick elevatoring that also transports you forwards. Requires lots of luck or some more systematic method.

Combining elevatoring with a slow-fall potion may make it a bit faster or make it possible to mantle stuff earlier.

Breaking a Fall: Outside of slow-fall potions, dropping items mid-air, and landing on ramps, you can break your fall by jumping onto people, [destroyed] bots, monsters and bodies. When frogbeast eggs are available, you can use them to spawn a frog directly beneath you that will break your fall. Be careful though, you can still take some damage. Frogbeasting works best with 2 or more in your inventory; trying with only 1 in your inventory is very risky, as it doesn't break on Garrett.

You can also use any other item you can throw, e.g. orbs and mines, to break your fall/get bumped on the side. This is easier than trying the same by dropping them in many cases. Doesn't work with flares because you only hold one activated flare in your inventory at a time which means there isn't a collision.

Quick mantling: When you mantle things you often don't have to hold the jump button the whole way, rather you should interrupt the process and you'll get teleported the rest of the way saving some time every time.

Long jumps: the way to get the longest jumps is probably to drink a speed potion first, then ready a slow-fall potion and quaff it immediately after jumping. If you do it before you might lose some speed.

You can jump off the bottom of a body of water to be able to surface a little sooner.

Boosts

With all the tricks that gain you extra speed, in order to make the best use of it you should be hopping to avoid losing it to ground friction any earlier than necessary. Practice jumping right after getting the boost. Drinking a slow-fall potion as soon as you're in the air might also give a net time save because you keep your higher velocity for longer when you touch the ground less even if you have to endure a short period of slow running.

Door boost: The game doesn't handle half-open doors very well. If you only open (or close) a door half-way and lean against it, you get a massive boost in the direction the door is pointing. Hope this works for NewDark too :P

Slant Boost: This requires an object with a slanted rising facet, e.g. a half-open crate lid (crates in mission 2) or bay door (also mission 2). To activate it, you need to get underneath it, crouch, then uncrouch or jump and you get sent pretty far along the slanted surface. The bay doors even get you sliding along the ceiling for a little bit before you fall off. The effect can be increased by consuming a slow-fall potion after the jump except with the aforementioned bay doors because it gets you stuck in them.

By adjusting the exact angle of the open lid or other object, you can get boosts giving you varying heights and distances. Also with the bay doors you can use the bottom of the door instead of the side.

Lean Boost: This can happen when leaning into a variety of objects, including ladders, turrets or bay doors and crate lids. If you got stuck on the object instead of leaning through it, you get sent in the direction in which you're leaning when you've rotated your view far enough out. Unleaning (which is something you can do at any time when in the air) will have the same effect in reverse, i.e. you'll be sent in the direction opposite to where you first leaned.

A particularly useful way to apply Lean Boosting is to jump into the object first immediately after having leaned so that when you unlean, you get sent in the initial lean direction AND you're in the air meaning you get carried further.

You can combine a slant boost and a lean boost to get neat effects that both send you up and sideways (even being able to change directions when stuck in the ceiling and unleaning). If you do this well enough you should be able to guide yourself onto the upper walkway of the inventor's shop (Cid Capezza) in mission 2, on the left side. You have to move the view so when you unlean you change directions.

The lean boost is highly reminiscent of the gate boost and might be based on the same exact glitch.

Gate Boost: If you're crouching underneath an object that's rising up, such as a portcullis, and you stand up as it's rising but already above your head, you get stuck in it in a strange way. If you then lean in any direction you get a varying but generally quite big boost. This works the same when unleaning if you wanted to do that for some reason.

Ramp Boost/NPC Boost: Speed boosts can be gained from landing on sloping surfaces, and even more speed can be had when jumping again as soon as you land on the slope. The speed gain is proportional to your falling velocity. You also take less fall damage (up to none) and make no noise. Falling on NPCs has a similar effect.

Rope Arrow Boosts: If you're climbing a rope next to a solid object [other than a wall] and you bump into the object you can get a big boost up or down the rope. If you're next to an object and then rotate the view [rapidly], you either get the same effect or a massive boost in the direction away from the object. Doesn't work with nearly all objects unfortunately so you just have to scout around. For an example, the hanging lanterns on the ceiling inside the storage house SE of Garrett's house in mission 4 are good for getting boosts and SHASing.

If you also jump off the rope as the boost is happening you very very frequently get SHASed, but occasionally you can get boosted instead. And the nice part is this doesn't seem to be nearly as particular about where you do it, which means you could get more utility out of your rope arrows. It seems if you jump when on your way down (as normally happens when bumping on things above you while hanging off ropes), it keeps your momentum and you smash on the ground dying instantly. Probably the only thing normally preventing this when you don't jump is the rope's hit detection kicking in before you hit the ground. I presume the same will happen moving upwards.

Looks like it's still varying levels of easy to get the SHAS/boost this way depending on what you're rope boosting off.

Object Boost: Stand in front of a sufficiently high object (lamppost, statue etc.) so you're close to one of its perpendicular hitbox corners. Lean around the corner so you're facing the object diagonally (don't lean too far). Now jump. When you land, you should be sent back the direction you were standing. If done ideally, the speed you get is higher than your normal running speed but not by much.

There's another type of object boost. If you have an object that's a height that allows you to lean over it while jumping but not too low, if you release lean and mash jump when falling it will fling you towards the side. At best the distance is greater than a normal running jump would allow but the timing and height of the object is very strict. It works well with the middle-height gravestones in Eavesdropping. On Shipping there's a vase stand thing next to the building A main entrance (the double doors) that gives you at best a huge boost if you lean more towards the wall so so you're not leaned too far over it when you jump.

The locks around mission 2 also seem to work very well for object boosting in the alternative way.

NPC Lean Boost: Leaning into NPCs also gives you a small boost. Hard to exploit.

"Stuck Boost": The jagged rocks that form the ceiling of the low gap leading into the narrow South area on Blackmailed (with the graveyard) are something you can get stuck on. When you do, if you keep running [diagonally] through the gap while uncrouched, and especially if you also mash jump, you get progressively more and more bent over, until you emerge on the other side at which point you get hurled forwards at a high speed. Might save time even though you're stuck for a bit. Doesn't seem to work with smooth ceilings.

Currently no other known uses but they haven't been sought after very carefully at all.

Lean zip: Lean left or right while facing something you can mantle. If you're also near a corner of that object or wall, when you press jump you might be zipped instantaneously in the direction you were leaning. If you were next to a wall, this can place your view inside the wall for a frame or two. It might be possible to zip right through something using this technique (aside from a regular crouch-mantle door transgression) but this requires finding suitable locations, none of which are known as of yet.

Items and Objects

Potions

Slowfall potions: they'll let you fall slower (instantly halves any negative z-velocity), but they also slow you down on the ground (by 50%) which is why you normally have to just take as much damage as you can afford to and put those healing potions to use. Or use other techniques to prevent fall damage. On the other hand you can get longer jumps the more slowfall potions you drink in the air.

You can jump higher than normal using a slowfall potion. If you're airborne while you quaff one (just after jumping), you will keep your horizontal velocity and get most of the height too.

Also, when you're underwater you can drink one to suddenly increase your effective buoyancy by a lot. The deeper down you were the more speed you'll be able to accumulate by the time you hit the surface. You might be able to reach a ledge that you otherwise couldn't this way.

Slowfall potions cause you somehow to dislodge from things you're stuck in (check the source code section of the guide for more on this). Unfortunately you are also forced off ropes.

Speed potions: they'll let you run at twice the speed for 8.6 seconds. So if you take 9 seconds to get one, you're wasting time (unless it allows for some other tricks such as crossing a large gap). Remember to start hopping right before you run out of its effect to keep the higher speed for a little longer.

- Infinite Speed Potion/ISP: This only works on Soulforge due to a special 'FlickerTrigger' present only in that mission. What is said about speed potions applies to slow-fall potions too, but not invisibility potions. All this was worked out by WheretIT:

Demonstration of the ISP If this setup doesn't work for you ask about it in the thread. You should be able to move around in the starting area and outside if you never cross a trigger line right next to where the demonstration stops running ahead.

The way timed speed potions work: - Activate effect: 'DrkInv.AddSpeedControl("Speedy", 1.75,1.25);' (Effects do not stack) - Create a timer named 'PreEndPotion' after a duration of 7.6 seconds - When 'PreEndPotion' triggers, play deactivation sound (optional) and create a new timer 'EndPotion' with a duration of 1 second - When 'EndPotion' triggers, the effect is removed: 'DrkInv.RemoveSpeedControl("Speedy");'

A timer object is a numerical handle that is stored in 'PotionTimer' property of a SpeedPotion. When the last activated SpeedPotion ends, the 'PotionTimer' property is cleared.

If a potion is already activated, the current timer is removed and all steps described above are performed.

While it might not be the only way, but the way the glitch happens on Soulforge has to do with a certain TrigFlicker (FlickerTrigger) object that is only used on Soulforge.

Now it gets a bit complicated... I'm still figuring out the exact order of events, but basically, this object is incorrectly implemented - it also uses a timer and stores the handle in the properties. The issue is the way it removes the timer when it is no longer needed - it can remove the timer using a numeric handle more than once.

So, the infinite potion glitch happens when after a save/load sequence, the speed potion you activate receives the same handle ID as was used before the save by the FlickerTrigger object, and soon after load, this FlickerTrigger object removes the speed potion timer.

Detailed explanation of what happens when Soulforge is loaded up on Normal difficulty:

-Level starts
-Scouting Orbs create their 1 second timers (#2/#3)
-Game creates some internal timers (#4-#18)
-Game is saved
-Game is loaded (last active timer is #18)
-Scouting Orbs create their 1 second timers (#19/#20)
-1 second after load, Scouting Orb timers expire
-4 seconds after the level start, TrigFlicker creates a timer (#21)
-8 seconds after the level start, TrigFlicker destroys a timer (#21)
-Game is saved
-Game is loaded (last active timer is #18 since timers #19-#21 have either expired or were destroyed)
-Scouting Orbs create their 1 second timers (#19/#20)
-I drink a potion that creates a timer (#21!)
-12 seconds after the level start, TrigFlicker destroys a timer (#21) and creates a new one (#22)

Aside from the starting area, the ISP can be activated in four other areas where TrigFlicker objects are used, but it is presumed that the starting area will be the ideal location for performing the ISP for any and all speedruns.

- You can also have both slow-fall and speed active at the same time on Soulforge but even if that was desirable to do, the setup would take too much time for usage in speedruns. Still you can activate either effect in any of the five TrigFlicker areas.

Mines and Other Explosives

Mines: You can blow up mines by throwing other objects (such as more mines) at them or with broadheads, rope, fire or noisemaker arrows. They have to get armed first unless it's a fire arrow you're using for it.

- You can "trap" doorways by laying down mines in the nook between the opening door and the doorframe (if it's wide enough). After they get armed, if an NPC opens the door, getting squeezed between the door and its frame tends to set the mines off. Ofc you can just lay down mines period, but door corners also catch the mines nicely if you want to throw them from afar.

- You can remotely arm a mine that's lying on top of another object by knocking it off it or by destroying or moving the object. It only gets armed after it's landed on the floor.

- Mines seem to be mapped under the same hotkey, i.e. if you've bound regular mines to 'm' but you don't have any, it will select flash or gas mines instead.

Arrows

You can sometimes fire a noisemaker arrow and make its sound play even after retrieving it. Not well understood, also unclear whether guards still hear it.

The damage dealt by broadheads is affected by their velocity. Because some of your momentum is added to the arrow's, you're causing more damage when firing in the direction you're moving.

You can cause a fire arrow to detonate mid-air if you throw something and the arrow collides with it. If it's the item hitting the arrow it just bounces off.

You can use any kind of arrow to hit buttons, including the hidden kind that involves dart boards and similar targets). This means if you're in no hurry to trigger the effect quickly and you have a spare gas or fire arrow, you could fire such an arrow faster than drawing the bow all the way because they'll hit the target even if they're flying slowly. Note that items may also be used. Useful in Soulforge at least and anywhere where you need to call an elevator and you have line-of-sight on the call button.

Remember that you can keep rope arrows that you've used (at the cost of some health) even if you need it to remove some height from a fall by just grabbing it as you're jumping off.

Miscellaneous

Object hitboxes: sometimes small objects (such as potions, orbs and bottles) have hit detection, sometimes not. This seems to depend on whether they're on top of another object (have hitboxes) or on a normal surface (no hitboxes). This isn't perfectly understood. If there's a hitbox, the objects can be climbed too.

Crates: Crates actually have an asymmetric hitbox that makes them have considerably more servicable surface area on their top and bottom facets than on the sides. To drop the crate on its bottom, face horizontally while dropping it.

"Carrying" more than one crate: You can just keep sliding them along the ground ahead of you. Could be good for performing a crate climb time-efficiently if you can't elevator.

You might also be able to use crates to create a higher jump off another type of boost but it seems very difficult to jump off a crate in full speed even when it's lying on its bottom.

- Crate stacking: stack crates to get somewhere you couldn't get before. You won't run any slower with a crate in your arms. Potentially a bit faster than slow elevatoring if you don't need too much extra height. The best way to balance yourself on a crate is to look down, drop it and jump as it's falling. This drops it on its side so it's not good for creating staircases.

In the highly unlikely scenario that you need to build a staircase out of crates (that you can get up or down), you should consider reading these instructions.

You can use items to get weight-triggered plates to activate or to stay activated. The items must all be in direct contact with the plate or their weight isn't applied. The weight applied doesn't seem very logical (a destroyed mech doesn't do anything)... You can also get the plate to bob up and down if one of the objects involved is lying at the edge and only touches the plate when it's raised.

You can throw items to achieve the same effect as arrows in any of multiple places where an arrow causes something to happen, e.g. accessing the loot stash in the art gallery of mission 2. All kinds of buttons are activated when an items hits them.

Flash bombs penetrate windows, doors and portcullises as if they weren't there.

Scouting orbs can be used to trigger [at least some] proximity-based conversations. Observed (in v. 1.07) with the guards on the 1st floor next to the meeting hall in First City Bank and Trust. Other conversations are clearly set to initiate when the player passes a certain trigger line (perhaps entering the relevant sound zone, for example room) and the orbs do nothing for those.

You may sometime be able to drop an item somewhere you're going to pass through later, then collect it again when you return simply to select it faster and more easily.

Use auto-search = on for looting bodies quicker. May only work if you were able to reach the item from where you were standing. Also note that you can disable auto-equipping items.

Dropping or throwing an item is one way to create noise. It's faster than drawing the bow.

Moving While Orbed: While entering orb view, you can still carry on e.g. jumping or strafing if you had the relevant button held down when it happened and if you were airborne.

General Tricks

Don't overlook the Thief 2 console for use with testing things efficiently.
- For some reason when I edit my user.bnd (on v.1.07 on a WinXP) and try to save it, something causes the text file to lose its line breaks which confuses the game. One way to fix this is to manually insert a line break after each line so there's an empty line in-between.
- Some of the more relevant commands: (sadly I couldn't find anything truly useful)

- cash_bonus X (not console command: put in dark.cfg or user.cfg to get X extra cash at the start of each mission)

- Don't forget to undo all changes before recording speedruns!

Leaning: This can only be done while on the ground. Running forwards or backwards or landing cancels the effect but not sidestepping. No matter which way you perform a lean, the effect should be identical. When unleaning (when lean is released) the mechanics seem to be exactly the same again except in the opposite direction and you can actually unlean while airborne. Visible in Lean Boosts and Gate Boosts. Remember that the unlean direction depends on which way you're facing just like leaning.

You can't crouch while leaned.

The game handles

When you have a velocity, it's added to any items you drop or arrows you fire.

Thin Walls/Ceilings: it is sometimes possible to grab items/push buttons/pull levers through the wall. It is also possible to attack someone through a thin wall or door. Furthermore you can drop items through walls or ceilings.

Also read the text about door transgression.

Glass breaking: you can break glass with your weapons or by jumping onto it (jumping through only works in v.1.18 and later).

Door blocking: you can block doors from closing by placing an object next to it. This comes in handy in a mission in Thief 1, but it's not know if it is usable in Thief 2.

Portcullis blocking: you can similarly block portcullises and anything else using an item with a hitbox.

Forcing open a door: there are several ways to force open a locked wooden door: four overhead swings or 10 slashes with your sword, 2 fire arrows, 2 frogbeasts, 1 mine or 1 well-placed cannon ball will all work. Some doors with a metal texture are actually wooden doors, examples of this are the front door of Angelwatch and the door to the office in the base camp in Kidnap. Metal doors will open up using mines or fire arrows, but frogs don't work. This works in the Sold Out version of the game, there are other versions in which it doesn't work. A very obscure method to cause damage to doors (and other objects) is to find a way to acquire a lot of speed and ram into them yourself.

SHAS: The Sudden Heart Attack Syndrome is still a thing in Thief 2 in every version despite being much more rare. Its only relationship with speedrunning is it often happens in situations where if it went slightly differently or if you didn't crash into something, you'd have a lot of speed off some kind of boost (such as notably Rope Arrow Boosts).

Crouch-mantle (probably OldDark only): Crouch while facing something mantleable (or just an empty space), then jump. This can cause you to teleport a small ways backwards - or sideways if you're leaning sideways - whether or not you're actually mantling something. Used as the basis for door transgressions and such.

Glitching through doors = Door transgression (OldDark only?): By placing a rope arrow right next to a door (make the rope hang as close to it as possible and near a seam might also be the best), [running or leaning into it to make it swing inside the door?], then grabbing it and jumping off can lodge you inside the door. To get all the way through you'll need crouch-mantling which doesn't seem to work well or at all for NewDark. If you do manage to get mostly through, slowfall potions help you get unstuck.

You can even just crouch-mantle into and through the door without using a rope. Just crouch facing outwards towards either something that you can mantle, or empty space, and on one side and lean on the same side so you're squeezing yourself against the door. It seems easiest if you're squeezed into the corner between the door and its frame. Then jump. Garrett should make the mantle noise. If it failed to jam you inside the door keep trying, varying the angle. After you're partially inside, all you need to do to get on the other side is crouch, lean towards the side you want to go, and jump again. This might still not bring you all the way through but once you're mostly on the other side, drinking a slow-fall potion will do the rest.

In fact there IS a way to pass through using nothing but crouch-mantling. It seems you have to be on the wrong side of the door (where you're coming from), or at least around the center of the doorway, then go all the way on one go, otherwise you can't make the last little bit. But then even that has happened, just not very often. When you're inside the door, doing a crouch-mantle without leaning can also sometimes do something.

All in all the success rate, especially without relying on slow-fall potions, seems to vary a great deal from door to door or - more likely - door type to door type. The shape of the entryway might also well be a factor.

You can use a partial transgression (definitely available in NewDark) with the rope arrow method to be able to reach something on the other side of a door or tapestry without actually transgressing it. A slow-fall potion will free you afterwards.

Note that no-one has ever been able to attach onto a rope arrow while transgressing so the intuitive method of using one to detach yourself fails.

There's one more way of doing a transgression that seems to only work in NewDark, which is to simply drink slow-fall potions while running towards the door (look up so the door isn't being frobbed). Can't make it all the way through but can make it almost there.

Found a slightly different way to transgress (in OldDark again) that might be easier than before. It only works if the doorframe isn't very thick. Just stand with your back against the door near the side. Crouch, then lean towards the same side you're stood on and face slightly the other way so the wall pushes you forwards around the corner and slightly away from the door. After this move you view back to a centered position (straight away from the door behind you). Now jump, and it should send you all the way through very consistently.

Out-of-Body Experience: This is a very special event that can happen if you're most of the way through something like a door. The theoretical explanation is one half of Garrett's two-part player model has passed completely through (the bottom half with the legs) but the other half (top half) is still caught in a wall or object. You're able to walk around the place and can easily free yourself from the wall completely just by crouch-mantling. This will cause you to essentially teleport to the place your legs are at.
- No real known uses, but perhaps the tension between the body halves can be transferred into a big boost. Very difficult to set up so probably segmented only in any case. There is also a limitation of not being able to walk around corners on the side you're stuck on. In fact you can't seem to detach far off the wall at all. Crouching is difficult too sometimes.
- (LotBlind) Contact me if you want a save file (v. 1.07) for messing with this.

Mantling into an Object: You can in some situations mantle into a position inside an object such as a portcullis (works in Mission 4 in the canal at the Marketplace). If you could then glitch out of it on the opposite side you might be able to skip something that way.

Deep crouching: If you crouch while trying to enter a small space, hugging a wall may allow you to get in deeper while strafing in a certain direction.

You can simply run up a big barrel. Could be useful for a trick jump.

You can get to low-ceilinged places higher up than you if you bring a crate with you so you can crouch-jump up there.

You can start mantling and turn around to mantle in the wrong direction. No known uses.

In Eavesdropping if you lock yourself in the corpse pit secret and jump up and down a lot while having horizontal speed you'll sometimes glitch through the slab for a split-second. This allows you to hit the lever again to free yourself. Could this be used for something elsewhere?

You can use block to cause a noise if your blackjack or sword hits something like a lantern. This is faster than swinging the item and you can ready the weapon for it in advance (so just moving in position causes the noise).

Taking a screenshot (either using the in-game bind or when doing it with external software) can inexplicably affect the game state in a way that can sometimes get you unstuck. Less reliable than slow-fall potions and has never been successfully used to complete a door transgression.

Crouching to detach from ladders has been a thing since v. 1.19. Unknown if this works with ropes too.

Use manual zooming (from menu) to avoid the wait on any long range shots. Also doesn't reset the zoom after taking the shot.

Making noise without wasting time: drop or throw an item or clang something with the blackjack.

If you need sound cues for something difficult to make out, turn ambient sounds off.

Guards and Other NPCs

The behaviour of guards isn't affected by items. For example: throw a burning flare in their face, they don't notice unless the object made a noise. Block their way with crates etc.
Guards can't open a locked door if they haven't got the key for it, but they certainly can if they do. In Blackmail they CAN open the gear doors even without gears.
NPCs have some randomness in their search patterns which means you can manipulate them to open doors quicker etc. in segmented runs with save/load.
Guards have to be really close to sense you presence when your fully invisible, and they also have to be really close to hit you with their sword/hammer/mace.
Guards and other NPCs can fall off ledges sometimes when wandering too close.
It only counts as a pickpocket if you get the loot before an unconscious NPC has fallen to the ground.
Unlike civilians, guards can't be knocked out with the blackjack if they're aware of you. (In v.1.07 they can, just stay behind their backs for a bit)
To kill an alerted guard fast: throw 2 frogbeast eggs in his face or do an overhead swing and two sideswings in quick succession.
Turn on auto body search to quickly grab the key off a corpse, no chance of accidentally picking up the corpse unless the key/item was out of reach. Might wanna turn this off on Kidnap.
Even while you're carrying someone, guards can't keep up with you. Take advantage of this in Kidnap.
If you want to pincushion guards with arrows while they're chasing you, you can right about evade their swords by strafing left/right and backwards while tapping the attack bind for as short a time as you can.
Guards don't seem to start their cycles until you pass through a trigger. Their AI is also partially frozen ("dozing") when you're far away from them, causing them to ignore things that would normally cause them to go on alert.
Noisemaker arrows cause guards to ignore most other sources of noise for a while. The same effect is apparent when they're having a conversation. Particularly useful on Casing the Joint.
After triggering a conversation between two NPCs, if you save/load you can get it to last longer if that's beneficial for manipulations in a segmented run.
You can manipulate enemies into using the same attack animation repeatedly, manipulate them into lunging forward, blocking, etc. and some of those are actually useful in some extreme circumstances.

The Mechanist Children

Mechbeasts and watchers are temporarily blinded by a flash bomb.
Combat bots can be distracted with noisemaker arrows (or other sources of sound).
Combat bots can be destroyed with a single fire arrow if they're unaware of you, though not consistently. They can also be destroyed with two frogbeasts while unalerted, but again doesn't always work. They can also be disabled with a single gas arrow to the furnace, or two water arrows.
Combat bots lead their target; spider bots and sentries do not.
Sentries can see farther than watchers.
Watchers can't see what's underneath them. Sentries also have a blind spot, roughly the 90 degrees behind them.
Little mechs have their eyes closed and don't react to touching them, only sound.
You can manipulate bots to hit other NPCs or fire cannonballs that explode next to a door etc. that you want to burst open.

Mission-specific (but not category-specific) notes:

Running Interference

You can blow the birdcall as soon as you start the mission. Don't do it too quickly or it will take about 20 seconds for Basso to go. Instead, use it when Basso has walked into place and leans back, he will then run off immediately.
- Alternatively, if you DO blow it immediately, his move is delayed which means you can cut him off right as he's about to enter the building having secured Jenivere in the meanwhile.
You can knock on Jenivere's door to alert her and cause her to run out of her room as if Basso had come to unlock it. You need to hit a spot around the top left corner. The noise the spot makes will be much quieter than normal but it can also work with a loud sound sometimes.
- Another way to alert Jenivere is to run into the door while blocking.
- Yet another way could be to get an archer to fire an arrow at you, make it hit something it will stick to, retrieve it and quickly fire it at J's door. Might save time because you don't have to run all the way to it and back.
- Also dropping the key at a door (such as Jenivere's) can cause the required clang.
It is sometimes even possible to set Basso on the job and make him complete the Jenivere rescue goal without doing anything yourself (observed on normal difficulty in 1.07 but suspect this to work with all versions). If you want to do this you're better off hiding to the west of the archway leading into the outer perimeter of the house so the guards are "dozing".

Shipping ... and Receiving

You have to get to the office even if you already have the required loot.
Most of the orange locks in building A can be opened from the other side of the wall. When a tutorial pops up telling you to use your lock picks (normal difficulty setting) you know you've highlighted the lock. Alternatively look for when the door itself is unselected.
- Doors you can open: Cid Capezza, Lady Vangelica, E.B. Bramrich (please fill in)
In Gilver's office, you can grab the diamond without slashing down the banner.
You can do big slant boosts in this mission off half-open bay doors (and crate lids of course) Sometimes you can do something that makes you stop half-way and be stuck for a little while before falling again.
Using the other down-facing facet of the door object (the bottom) for a similar boost works too. If in either case you get permanently stuck in the door, just hit the screenshot key.
A slow-fall potion will exaggerate the effect for a really long boost.
You can make the jump from the stack of crates to the South of your starting position (by the ladder) over to the higher stack around the starting zone by lean grabbing.
If you half-transgress one of the doors to the shacks you can fire arrows or throw objects at the numbers to activate a bay door.
You can do a lean boost off a bay door if you open it wide enough so there's a gap to slip yourself through. The speed is pretty ridiculous. There's also slant boost opportunities off the same doors and off crate lids.
You can object boost off the little pedestal thing leaning on the wall to the left of the main entrance to building A. At best gives a huge boost. Best way to do it is to lean forwards while facing an angle between the wall and the thing, then jump and jump again as you land.
Lady Vangelica's store has a regular lock instead of

Framed

You don't have to go to the hall of records to get the code. It's always 4026.
If you 'elevator' yourself up the buildings at the start, you can get up onto the wall. From there you are able to climb onto the roofs and go round counter-clockwise. Finally you'll be able to cross the moat using a slow-fall jump (drink immediately AFTER jumping). Traverse a section of the perimeter wall to access the courtyard.
If you have access to the items, the faster new way of entering the front courtyard is using an invisibility potion to get to where the front sentries are unharassed and a slow-fall potion to jump high off and mantle the perimeter wall directly. The most common way to do this is to aim for the right-hand lamp on the perimeter wall. This mantle is particularly finicky about which direction you are facing. Isn't 100% consistent?
The switch to the gate (with the two archers next to it) can be reached from the outside. If exiting the police station via this route you don't have to open the gate; standing next to it is enough to complete the objective.
The walls around the two outside courtyard areas at the main gates and side entrance have unfilled geometry that allow you to pass through if you needed to get from the one the other or on the perimeter wall for some reason. (observed in 1.07)

Ambush!

Items in Garrett's stash can be picked up through the wall while it is going up.
You have to get the gate key even if you have already passed the gate by going OOB (the gate can even be mantled).
Speed boosting on the sloping streets will shave a few seconds off.
There's opportunities to get on the rooftops either by elevatoring or just by finding windows with wooden frames and roping your way up.

Eavesdropping

The seed for the key location is based on system time upon initiating the mission and thus cannot easily be manipulated outside of segmented runs.
The possible key locations vary from difficulty to difficulty.
You have to overhear the conversation even if you already have the required loot and made a wax impression of the key.
You cannot run away from the door or you'll get a mission fail.
In v. 1.07 there is actually a way to get away from listening to the conversation but its uses are very limited. You have to climb the flat door canopy above the outside door you can normally listen in on the convo around and trigger it there. Avoid moving backwards or to the sides, instead mantling the high rooftop and you can get away from the door that way. Here are some more details:
- If you pass one of several fail lines around the map it causes an instant fail. The ones just around the doors work as examples but there are (for whatever reason) more of them than that.
- You can also get a fail if you're too far from the meeting hall whenever the conversation "chunk" changes. The chunks are about 15-40 seconds long segments of audio that you can recognize by the game going back to the start of the chunk whenever you save and load. During each chunk you can go anywhere so long as you're back within earshot by the time the next one starts playing. Note that when you save/load and the chunk is reset the game also performs the check then so you cannot do that anywhere you're not supposed to be.
- The areas that constitute being within earshot are immediately around the doors, the yards on the N, E and S of the meeting hall and the rooftop with the shed. You can't actually hear the conversation from every corner but the game doesn't mind.
- Going indoors if you triggered the conversation from outside always instantly fails, this includes all the sheds and the laboratory and also the room connecting to the E balcony and the entire W balcony.
- In essence the best it seems you can do with the skip is get a bit closer to wherever you want to be next. You can loot the shed rooftop although the catch is meager. You can try to take out some guards and children if you like.
- The first sound chunk (bell tolling) can be heard from anywhere on the map. For this reason it's possible to go anywhere you like (some fail lines seem to be disabled) so long as you keep resetting the chunk by save/loading and avoiding going indoors or hitting still active fail lines. Unfortunately this also delays the conversation indefinitely.
- Elevatoring off the door canopy into heights fails in the later versions.
If you collect the right key after the conversation is finished without having heard where it is Garrett will comment on it letting you know it's the right one. It also goes into a different stack from the others (which generally seem to form about 3 different stacks in your inventory). You can only make one wax impression at a time so you need to know which one you'll need.
In v. 1.07 there is a piece of loot (a small hammer) lodged physically inside one of the sarcophagi in the catacombs. It's the sarcophagus next to the pile of bones and the purse. You can grab it by groping about near the floor at the center.
For style points you can drop the wax impression after completing the other objectives and it doesn't prevent succeeding at the mission.

First City Bank and Trust

You don't have to go to the hall of records to get the vault number, even though your objectives say so. It's always 11.
If you get stuck on the window leading to the basement, it's probably because the handle is blocking you. Hug the window frame to pass it. If that doesn't work, try closing and opening the window. The window is actually made of wood, so you can force it open.
In version 1.07 you can force open the vault door with explosives, it will go right through the metal bar.
You can collect the recording without opening the safety box.
The fastest solution for unbolting the vault door has 3 steps: use the middle left, middle right and bottom right buttons in any order.
The goal of exiting the bank can be completed by climbing up towards the top of the dome on the inside. Also reaching any balcony or the rooftop works.
You can climb the ornamental yellow and white lamps in the fully marbled room E of the corridor leading to the vault to reach the second floor.

Blackmail

The watchers at the start are attached to wooden beams that you can stick rope arrows in.
You have to trigger the conversation between then guards on the 3rd floor where they uncover Truart's dead. You CAN do this after visiting the room though. They will still talk even if they're in full alert (and chasing you) so long as they're still alive.
The guards passing through gear doors in this mission cannot re-lock them once they're through meaning it's extra useful to try to lure them into opening them. They do NOT need to have the gear in order to be able to open the doors.
The torture room has distinct differences in v. 1.07:
- The dead lady is a zombie instead. She still has the purse, which you can snag through the bars. The bars next to the rack are stuck, the button will not withdraw them. The reward for killing the two spiders is a gas ARROW not gas mine.
1.07 has an exit zone to the south in the secret corridor leading to the graveyard secret. Makes for a much faster exit than entering the streets.
The jagged rocks that form the ceiling of the low gap leading into the South corridor (with the graveyard) are something you can get stuck on. When you do, if you keep running [diagonally] through the gap while uncrouched, and especially if you also mash jump, you get progressively more and more bent over, until you emerge on the other side at which point you get hurled forwards at a high speed. Might save time even though you're stuck for a bit. Doesn't seem to work with smooth ceilings.
The door in the main entry hall of the estate to the second floor can be opened by using the Jenivere trick from Running Interference - hit the top of the door with the blackjack and the guards on the other side should open it for you.
- Alternatively, it is possible to alert the guards on the other side by firing a broadhead arrow into the door. Hitting the slightly dark section below the handles is relatively consistent, although the arrow won't alert the guards if it happens to go directly between the two doors (it won't make a sound).
Managed to mantle from inside one of the fireplaces in this mission outside it after leaning inside and just trying to mantle in various directions. Only seems to work in .07 or OldDark in general.
You can transgress the outside gates fairly quickly (in two goes). The gate from the streets to the estate grounds is also possible to transgress with one crouch-mantle and a slow-fall potion.

Trace the Courier

Lt. Mosley and the pagan will stand in one place from time to time to check if they're being followed. Usually Mosley only does this once in the beginning, you can avoid this by exposing yourself a little bit, she will then skip this. Putting out torches in front of her (she doesn't have to see it happen) distracts her further and she won't stop at all.
You can't get too far away from the letter, but when you have it in your inventory you can run around the whole map without failing the objective, at least until the pagan notices that the letter is missing.

Trail of Blood

There is a speed potion above the second red gem (normal) that doesn't take too long to obtain.
Speed boosting on the slopes in the beginning of the level, at the start of the Maw, and on the grass leading down to the pagan is a good idea.
Using a combination of a speed potion and a slowfall potion (can be picked up near the face portal) will skip a lot of time in the Maw by ramping up and over a large gap, grabbing the edge (or sometimes even making it all the way without mantling). This can be difficult to do consistently and is highly dependent on timing and angle.

Life of the Party

You don't have to activate the voice machine in Karras' office.
One of the guards guarding the fort (with the merlons) has a red key that you can use to open the room with the scripture.
You can climb onto the bank's roof from the east side and make your way south from there. When you've reached the end of the roof you need to crouch in order to get any further, there's an invisible ceiling.
If fast enough, there is a guard that exits the room with the scripture, and you can open the door again as it's closing.
Golden boy can be blocked by dropping a crate in the doorway to the pantry. Two crates can be found just inside the pantry, in a corner.

Precious Cargo

There are two fire arrows at the beginning of the mission, sitting on a window sill, and can be used to blow open the door to the freezer if none were purchased.

Kidnap

Speed boosting on slopes is beneficial.
The locked metal double doors at Site 5 leading to Cavador close automatically after a certain amount of time. It is possible to KO Cavador and carry his body back out these doors before they close. However if you're too slow, the doors will close and you'll have to drop Cavador to open the door again.

Casing the Joint

When you blind an unalerted guard or servant with a flash bomb, it doesn't count as a 'confrontation'. (This DOES count as a confrontation in later versions of the game, at least on v1.21)
You can exit the mansion by breaking a window. When you're on the east side of the second floor, positioning Garrett just on the outside of the window frame counts as 'exited'. You can climb into the mansion through some of the windows with unbreakable glass (with the metal grates), your position has to be just right and you'll go right through. (This might be earlier versions only, as it does not work in v1.21)
It's possible, with the use of a crate, to elevator up to the second floor, and using a vine arrow, to gain access to the third floor.

Masks

You can exit the mansion by breaking a window. When you're on the east side of the second floor, positioning Garett just on the outside of the window frame counts as 'exited'. You can climb into the mansion through some of the windows with unbreakable glass (with the metal grates), your position has to be just right and you'll go right through.

Sabotage at Soulforge

You have to read the correspondence from Karras to brother Kelsus, even if you put the guiding beacon in place and all of the signal towers are using signal B.
There are many places to frogbeast in this mission. Steel plates can also be used to break your fall, and they are reusable.
It's possible to clip through the gate at the top of the beacon tower, and frob the lever to open the gate. Straferun into the gate, and as soon as contact is made, stop running, and lean into it.
If your aim is good, it's possible to hit the elevator down button as you enter the pillar room. It's also possible to hit the down button at the next elevator (where an iron beast is guarding it).

Side notes

In Thief 1, you accelerate after every bunnyjump. In Thief 2, you can keep up your velocity (speed potions) by bunnyhopping and you can increase it a little bit by hopping on a sloped surface (going downhill).
The levels are different depending on the version you have. In principle any version that's the fastest can be accepted. Currently (April/'14) all the recent runs have been on 1.18 (or rather the GOG version which has the fan patches as well bringing it to, as for now, v. 1.22). There are some glitches present on 1.07 that might help bring down the times even further. v.1.00 hasn't been explored at all. However, because the presently available versions are all 1.18, any runs on earlier versions will go under a different category. If the choice is arbitrary, or nearly so, you should run v.1.18.
Fraps doesn't capture the menu screens because they are rendered with DirectDraw (it does record the audio in the menus). This isn't really necessary because you can see in-game what difficulty the level is by counting the health shields, but it does make determining the time more difficult, as the final time is displayed in the stats screen after the mission. So unless you use a recorder that can properly record DirectDraw (like this one), you have to time it manually. (Fraps has worked well with v1.21 of the game)
If you use ZD Soft Game Recorder to capture, be sure to use a custom video size, or else it will default to 320x240 (or 640x480 if you capture at full screen size). This is because the menu size is 640x480. Of course this doesn't matter if you also use 640x480 in-game.
On modern hardware, the Dark Engine might look like ass. There is a utility to fix this, ddfix. I'm not sure if it will be allowed though, as it modifies certain game files. AFAIK, gameplay is unaffected. This utility also fixes problems with multiple cores and hyperthreading. (not sure about this one currently) - The Steam and GOG releases of the game come with ddfix.
There is also a utility that lets you play Dark Engine games (like Thief) in widescreen. Again, I'm not sure if it will be allowed as it modifies certain game files and also isn't mandatory for recording. You can get it here. If you use it in combination with ddfix, be sure to install ddfix first. (probably not allowed at all, affects gameplay in a sense) - ddfix allows custom resolutions
Fogging may look ugly on newer graphic cards, fortunately it can be turned off. If it looks good, you still want to turn it off on Life of the Party because it's broken in that mission.
When hardware acceleration for audio is enabled, only the ambient sound is captured. Turn it off while recording.
Keyholing is believed to be impossible for Thief II although there is a mention from Lytha that she managed to do it with "old-style door", presumably meaning there's a kind of door used somewhere in T2 that was present in T1. If you manage to do it let us know in the thread. Here are a set of instructions (by Luthien, 2002): http://dominikvogt.gmxhome.de/guides/keyholing.txt. For completion's sake this is Lytha's notes about how to use keyholing to "transgress" a door in T1: http://www.lytha.com/games/thief/knowledge/Doors/index.html. Note that v. 1.07 (and possibly 1.18) do allow you to transgress some doors using a bug in the mantling engine that sends you backwards when attempting to mantle nearby things and completing the process by quaffing a slow-fall potion.