Mighty Bomb Jack (NES)/Game Mechanics - Revision history

Ktwo: /* Counters (and RNG) */

2025-09-01T08:11:09Z

‎Counters (and RNG)

Ktwo: /* Transformed enemies */

2025-01-21T08:04:42Z

‎Transformed enemies

Ktwo: /* Mummies */

2025-01-21T07:58:44Z

‎Mummies

Ktwo: /* Items */

2025-01-21T07:50:49Z

‎Items

Ktwo: /* Items */

2024-11-16T09:43:21Z

‎Items

Ktwo: /* Items */

2024-11-14T15:12:36Z

‎Items

Ktwo: /* Items */

2024-11-14T15:12:17Z

‎Items

Ktwo: /* Transformed enemies */

2024-11-13T10:26:37Z

‎Transformed enemies

Ktwo: /* Transformed enemies */

2024-11-13T10:23:33Z

‎Transformed enemies

Ktwo: /* Transformed enemies */

2024-11-13T10:23:15Z

‎Transformed enemies

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 ===Counters (and RNG)===
 The game does not appear to have any RNG addresses or algorithms (but a deeper code analysis would be needed to understand seemingly random behavior in the game). Counters instead play a major role in creating randomness and item spawns:
-* Bomb counter ($356) - Collecting a bomb increases the bomb counter by one or two. When the value reaches 20, a P-ball (see the [[Mighty_Bomb_Jack_(NES)/Game_Mechanics#Items|item section]]) will spawn in the center of the room (when in a palace room) or the next opened chest will produce one (when in the corridors). The first bomb in a room is always worth 1 bomb point. There is then a "next bomb" in the order, which gives 2 bomb points. In the palace rooms, the next bomb is the one that's lit. In the stages, it's not always easy to know which bomb is the next in order, but it usually follows the stage layout. Other than giving 2 bomb points, these bombs also give a different sound when collected. The bomb counter can be reset in three different ways:
+* Bomb counter ($356) - Collecting a bomb increases the bomb counter by one or two. When the value reaches 20, a P-ball (see the [[Mighty_Bomb_Jack_(NES)/Game_Mechanics#Items|item section]]) will spawn in the center of the room (when in a palace room) or the next opened chest will produce one (when in the corridors). The first bomb in a room is always worth 1 bomb point. There is then a "next bomb" in the order, which gives 2 bomb points. In the palace rooms, the next bomb is the one that's lit. In the stages, it's not always easy to know which bomb is the next in order, but it usually follows the stage layout. Other than giving 2 bomb points, these bombs also give a different sound when collected. The bomb counter can be reset in (at least) four different ways:
 # Complete a palace room
 # Collect a P-ball and let its effect wear out before leaving the room (timer in $6B/$6A - 256+64 = 320f)
 # Activate green Jack and let its effect wear out before leaving the room (timer in $6B/$6A - 256+64 = 320f)
 ''Note 1: Any bombs collected while the P-effect or green Jack are active will not add to the bomb counter''<br />
 ''Note 2: If Jack leaves the room before the timer has finished counting down (#2 and #3), the timer will be reset to 0, but the bomb counter will '''not'''

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 [[File:Bird_mbj.png]] 5. Bird - Slow moving enemy that homes in on Jack horizontally and vertically. It can't move diagonally.<br />
-The enemy type is determined three frames before the mummy starts transforming. The game then takes the A-counter (see the Counter section) and calculates the modulus of 6 of that value (= the remainder when dividing by 6). The numbers in front of the different enemy types indicate these values. It's very much possible to manipulate the enemy spawns in certain areas (and it can also save time speedrun). Since the value is never reset, it's however also difficult to know its value at any given point in time. The best way to find out the value is to watch which enemy that spawns at a certain point and then start counting the A-presses onward. This is luckily well suited for the speedrun mindset, with a pre-determined route which often allows for a constant number of A-presses between two given points. Needless to say, stretches of gliding in mid-air with rapid A-presses make this harder to control.<br /><br />
+The enemy type is determined three frames before the mummy starts transforming. The game then takes the A-counter (see the Counter section) and calculates the modulus of 6 of that value (= the remainder when dividing by 6). The numbers in front of the different enemy types indicate these values. It's very much possible to manipulate the enemy spawns in certain areas (and it's very useful in a speedrun to set up certain rooms with specific enemy configurations). Since the value is never reset, it's however also difficult to know its value at any given point in time. The best way to find out the value is to watch which enemy that spawns at a certain point and then start counting the A-presses onward. This is luckily well suited for the speedrun mindset, with a pre-determined route which often allows for a constant number of A-presses between two given points. Needless to say, stretches of gliding in mid-air with rapid A-presses make this harder to control.<br /><br />
-''Important note: There is a discontinuity in the enemy type spawns as the A-counter loops. 255 gives a remainder of 3 when divided by 6, while 0 obviously gives a remainder of 0 when divided by 6. This means that two enemy types are jumped over in the cycle. A normal ending run will loop the counter near the end, while a best ending run will loop two or maybe even three times (depending on the category that is played). When routing a speedrun, one should try to avoid this discontinuity to happen during a section of enemy manipulation.''
+''Important note: There is a discontinuity in the enemy type spawns as the A-counter loops. 255 gives a remainder of 3 when divided by 6, while 0 obviously gives a remainder of 0 when divided by 6. This means that two enemy types are jumped over in the cycle. A normal ending run with warps will loop the counter near the end, while a best ending run will loop twice or more, depending on the category that is played.''

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 ==Enemy behavior and manipulation==
 ===Mummies===
-This section describes mummies in the palace rooms. Mummies in the corridor probably behave similarly, but their spawn locations are determined in a more complicated way (hasn't been investigated in detail).<br /><br />
+This section describes mummies in the palace rooms. The game mechanics for the mummies in the corridors haven't been investigated in detail. Their spawn locations are determined in a more complicated way. However, the spawn timing in the corridors is the same as in the palace rooms.<br /><br />
 <u>RAM-addresses of interest</u><br />
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 Once the mummy has spawned, the general rule is that it starts walking in the direction of MBJ (there are exceptions, see below). It walks back and forth on the platform until the drop timer has counted down. Next time it reaches an edge, it will drop down. If the mummy landed on another platform (and not the floor), the drop timer is reset and will start counting down again. Just like the spawn timer, the drop timers are room-dependent and mummies generally drop down faster as the game progresses.<br /><br />
-''Note: the movement direction address can be called from a second location in the code and revert the direction (meaning the mummy starts walking away from MBJ instead). The same piece of code can be called again, reverting back to the "normal" movement direction (so walking towards MBJ). This game mechanics has not been fully analyzed. However, player inputs can manipulate this. To study this effect, the following movie and instructions can be used (credits to 'SpaceColonizer'):<br />
+''Note: the movement direction address can be called from a second location in the code and revert the direction (meaning the mummy starts walking away from MBJ instead). The same piece of code can be called again, reverting back to the "normal" movement direction (so walking towards MBJ). This game mechanic has not been fully analyzed. However, player inputs can manipulate this. To study this effect, the following movie and instructions can be used (credits to 'SpaceColonizer'):<br />
 https://tasvideos.org/UserFiles/Info/638237798222671732<br />
 ''Truncate the movie at frame 17814. Mummy 1 goes right as expected.

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 * [[File:Crystal_mbj.png]] Crystal balls - There are two crystal balls in the game. Both are found in special chambers, where you need to break some of the blocks surrounding them. Picking up one crystal will unlock the queen's room and collecting both will also unlock the princess' room. In order to get the best ending, you need to collect both.
 * [[File:Secret_coin_mbj.png]] S-coins - Found in chests. There are in total 10 of these coins (appears to have been verified by code analysis, but reference missing). Collecting 5 of these will open up Belzebut's room at the end (only if both crystal balls have also been collected along the way). There is no point in collecting more than 5 S-coins (other than scoring points). Only green Jack can pick up S-coins (but there is no restriction on what form you need to be in to make it visible).
-* [[File:Sphinx_mbj.png]] Sphinx - Opens hidden/locked doors in the room they're found in. Sometimes there are more than one sphinx in a room and each one then corresponds to a specific door.
+* [[File:Sphinx_mbj.png]] Sphinx - Opens hidden/locked doors in the room they're found in. Sometimes there is more than one sphinx in a room and each one then corresponds to a specific door.
 * [[File:Power_ball_mbj.png]] P-ball - All enemies turn into coins for 320 frames. The P-ball is spawned when the bomb counter (see the section about counters) reaches 20. When the bomb counter reaches 20 during the stage, a jingle sound effect is played and the next opened chest will contain the P-ball (along with whatever it initially held). If it happens in a palace room, it will spawn in (or near?) the center of the room and start moving around diagonally.
-* [[File:B-ball.png|22px]] B-ball - Bonus points. Appears in a palace room when the score ($A3/$A2/$A1/$A0) passes a multiple of 5000. The B-ball does not appear in the corridors or as a result of the points awarded from completing a round. In the later rounds, where enemies spawn faster and there will be more objects on the screen, the creation of a B-ball often results in a lag frame (but usually not more).
+* [[File:B-ball.png|22px]] B-ball - Bonus points. Appears in a palace room when the score ($A3/$A2/$A1/$A0) passes a multiple of 5000. The B-ball does not appear in the corridors or as a result of the points awarded from completing a round. In the later rounds, where enemies spawn faster and there will be more objects on the screen, the creation of a B-ball often results in one or a few lag frames.
 * [[File:Extra_coin_mbj.png]] E-ball - Extra life ($3E4). Found in secret locations, but can also be triggered by gold coins (tracked in $0367). You need to collect 40 coins or more. The next time the score passes a multiple of 5000 in a palace room, the E-ball will appear (instead of the B-ball).
-* [[File:Mighty_drink_mbj.png]] Bottle - Increases the timer ($A4, supported by $229 for changing from hex to dec). Should be avoided in a speedrun as it costs time counting down after the end of each level (6f per "tick").
+* [[File:Mighty_drink_mbj.png]] Bottle - Increases the timer ($A4, supported by $229 for changing from hex to dec). Should be avoided in a speedrun as it costs time counting down after the end of each level (6f per "tick"). Note however that the timer is reset when transferring to a new corridor level without completing a palace room in-between. Some bottles can therefore be collected without time loss, depending on the route.
 <br>

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 * [[File:Sphinx_mbj.png]] Sphinx - Opens hidden/locked doors in the room they're found in. Sometimes there are more than one sphinx in a room and each one then corresponds to a specific door.
 * [[File:Power_ball_mbj.png]] P-ball - All enemies turn into coins for 320 frames. The P-ball is spawned when the bomb counter (see the section about counters) reaches 20. When the bomb counter reaches 20 during the stage, a jingle sound effect is played and the next opened chest will contain the P-ball (along with whatever it initially held). If it happens in a palace room, it will spawn in (or near?) the center of the room and start moving around diagonally.
-* [[File:B-ball.png|22px]] B-ball - Bonus points. Appears in a palace room when the score ($A2/$A1/$A0) passes a multiple of 5000. The B-ball does not appear in the corridors or as a result of the points awarded from completing a round. In the later rounds, where enemies spawn faster and there will be more objects on the screen, the creation of a B-ball often results in a lag frame (but usually not more).
+* [[File:B-ball.png|22px]] B-ball - Bonus points. Appears in a palace room when the score ($A3/$A2/$A1/$A0) passes a multiple of 5000. The B-ball does not appear in the corridors or as a result of the points awarded from completing a round. In the later rounds, where enemies spawn faster and there will be more objects on the screen, the creation of a B-ball often results in a lag frame (but usually not more).
 * [[File:Extra_coin_mbj.png]] E-ball - Extra life ($3E4). Found in secret locations, but can also be triggered by gold coins (tracked in $0367). You need to collect 40 coins or more. The next time the score passes a multiple of 5000 in a palace room, the E-ball will appear (instead of the B-ball).
 * [[File:Mighty_drink_mbj.png]] Bottle - Increases the timer ($A4, supported by $229 for changing from hex to dec). Should be avoided in a speedrun as it costs time counting down after the end of each level (6f per "tick").

← Older revision		Revision as of 10:26, 13 November 2024
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	The enemy type is determined three frames before the mummy starts transforming. The game then takes the A-counter (see the Counter section) and calculates the modulus of 6 of that value (= the remainder when dividing by 6). The numbers in front of the different enemy types indicate these values. It's very much possible to manipulate the enemy spawns in certain areas (and it can also save time speedrun). Since the value is never reset, it's however also difficult to know its value at any given point in time. The best way to find out the value is to watch which enemy that spawns at a certain point and then start counting the A-presses onward. This is luckily well suited for the speedrun mindset, with a pre-determined route which often allows for a constant number of A-presses between two given points. Needless to say, stretches of gliding in mid-air with rapid A-presses make this harder to control.<br /><br />		The enemy type is determined three frames before the mummy starts transforming. The game then takes the A-counter (see the Counter section) and calculates the modulus of 6 of that value (= the remainder when dividing by 6). The numbers in front of the different enemy types indicate these values. It's very much possible to manipulate the enemy spawns in certain areas (and it can also save time speedrun). Since the value is never reset, it's however also difficult to know its value at any given point in time. The best way to find out the value is to watch which enemy that spawns at a certain point and then start counting the A-presses onward. This is luckily well suited for the speedrun mindset, with a pre-determined route which often allows for a constant number of A-presses between two given points. Needless to say, stretches of gliding in mid-air with rapid A-presses make this harder to control.<br /><br />

−	''Important note: There is a discontinuity in the enemy type spawns as the A-counter loops. 255 gives a remainder of 3 when divided by 6, while 0 obviously gives a remainder of 0 when divided by 6. This means that two enemy types are jumped over in the cycle. A normal ending run will loop the counter near the end, while a best ending run will loop two or maybe even three times (depending on the category that is played). ~~In the best ending route that is/will be described here in the kb~~, ~~both times the counter loops occur close~~ to ~~sections~~ of enemy manipulation ~~and therefore need to be taken into account when planning the route~~.''	+	''Important note: There is a discontinuity in the enemy type spawns as the A-counter loops. 255 gives a remainder of 3 when divided by 6, while 0 obviously gives a remainder of 0 when divided by 6. This means that two enemy types are jumped over in the cycle. A normal ending run will loop the counter near the end, while a best ending run will loop two or maybe even three times (depending on the category that is played). When routing a speedrun, one should try to avoid this discontinuity to happen during a section of enemy manipulation.''

@@ Line 115: / Line 115: @@
 ===Transformed enemies===
-The mummies transform into one of six enemy types when dropping to the floor (these are not the official names, but the official ones would probably be quite confusing to use):<br />
+The mummies transform into one of six enemy types when dropping to the floor (these are not the official names, but are the ones used in this wiki):<br />
 [[File:Bat_mbj.png]] 0. Bat - Moves around diagonally without considering Jack's position.<br />
 [[File:Lobster_mbj.png]] 1. Lobster - Fast moving enemy that homes in on Jack. Only moves diagonally. (in most situations, this is the most dangerous enemy)<br />