Dragon's Lair (NES)/Game Mechanics(ntscu)

Dragon's Lair (NES)

Items

• D - daggers, deal 1 HP of damage, 3 can be on screen at the same time
• A - Axes, deal 2 HP of damage, 2 can be on screen at the same time
• F - Fireballs, deal 3 HP of damage, 1 can be on screen at the same time
• E - restore 16 energy
• C - restore candle
• G - Add one gold to the inventory
• L - Extra life
• P - Points

Hidden item locations

The list below comes from searching with save states, but hasn't been verified by address watching, so it's possible that there are still hidden items to be found.
Level 1 (in order of appearance)
A - right before the first two gateways
P - right after the first two gateways
F - after the third prisoner
A - before the second set of two gateways
F - after the last prisoner

Level 2 (in order of appearance)
C - in the opening in the roof between the first two moving blocks
P - two blocks to the right of the hidden C
P - after the first set of two moving blocks
A - before the first pit
L - after Singe's Dragon's Breath

Level 3 (in order of appearance)
P - under the second arc from the start
A - under the third arc from the start
G - before jumping on the ledge of the first pendulum
E - after the first set of two pendulums
L - after the axes
F - before the second ghost
E - right before the 3rd G
P - before the visible daggers
A - over the first floor support after the visible daggers
E - after the hidden axes
P - under the second arc after the big skull guarding a big pit
P - under the same archway as the above P

Level 4 (in order of appearance)
There doesn't appear to be any hidden items in this level.

Movement and animations

This section looks at the cost of performing various actions. If nothing else is stated, it's compared to walking in a straight line.

• First shot - 35 frames
• Subsequent shots - 20 frames/shot
• Small jump - 30 frames
• Big jump - 35 frames
• Small vertical jump - 95 frames
• Big vertical jump - 120 frames
• Dropping down "1 height" - 35 frames (meaning that it's 5 frames faster to jump off ledges than drop down from them)
• Duck and rise - 70 frames
• Go straight into ducking position after a jump - saves 15 frames compared to performing jumping and ducking separately
• End-of-level gold countdown screen (1 gold) - 157 frames
• Countdown for each additional gold - 24 frames
• Chaining jumps together, chaining ducking and rising, "corner landing" all have no additional impact on the animation times

Energy

The player energy is tracked in memory addresses 332 (big energy, BE) and 6A5 (small energy, SE). When the small energy loops, the big energy is reduced by 1. A life is lost when the big energy hits 0. Below are some observations about the energy.

• E block - +16 BE
• Getting hit by a bat, skull, the Lizard King or a bubble - -4 BE
• Shoot - -16 SE
• Start energy - 39 BE
• If the player's BE is 2, 3 or 4, getting hit by an enemy brings you down to 1 BE and whatever you had left of small energy, instead of killing you if it had inflicted the normal 4 damage.
• If an E is collected when player energy > 23, you'll end up with 39 BE and whatever you had left of small energy.

Note: There is a bug that can occur with the Lizard King. If you bump into him in the vicinity of where the first serpent was supposed to appear, you'll take damage continuously. In a speedrun setting (so walking to the right without stopping), that means a damage of 12 BE. If you stop moving while taking damage, even more energy will be lost.

Enemies

• Serpent - 3 HP
• Red bat - 3 HP
• Baby dragon - 4 HP
• All other regular enemies have 1 HP
• Dragon under the drawbridge - 10 HP
• Mine cart troll - 10 HP (each)
• Grim Reaper - 16 HP
• Singe - 40 HP

The RAM addresses containing the bosses' health tend to vary a bit, for unknown reasons. These are addresses encountered: 3B2, 3C4, 3FA, 3E8, BB2 and 40C. It's easy enough to find these addresses when needed, so no further attempt has been made to investigate if there are other possible addresses.

The Lizard King

At the time of writing, there doesn't appear to be a description of the mechanics behind the appearance of the Lizard King. However, RAM-address 718 is activated and starts to count down when the King approaches.
Below are a few observations from playing the game, but not verified through code analysis:

• There is roughly a 50% probability of the Lizard King occurring in level 1.
• It can only appear once in level 1 (same goes for level 2).
• If the Lizard King appeared in level 1, it's not going to appear any time before the dark section in level 2.
• The chance of a Lizard King in the dark area of level 2 is somewhere in the range 10-20%.