Addams Family (NES)/Game Mechanics and Techniques - Revision history

Ktwo: /* Items */

2023-01-16T13:21:59Z

‎Items

Ktwo at 13:16, 16 January 2023

2023-01-16T13:16:40Z

Ktwo: /* Exploiting poor hit detection of solid walls */

2023-01-16T13:08:45Z

‎Exploiting poor hit detection of solid walls

Ktwo: /* Rowing the boat on the secret river */

2022-09-12T21:59:07Z

‎Rowing the boat on the secret river

Ktwo: /* Ice physics */

2022-09-12T21:50:49Z

‎Ice physics

Ktwo: /* Swimming */

2022-09-12T21:50:27Z

‎Swimming

Ktwo: /* Swimming */

2022-09-12T21:50:03Z

‎Swimming

Ktwo: /* Swimming */

2022-09-12T21:44:32Z

‎Swimming

Ktwo: /* Useful RAM-addresses */

2022-08-18T05:57:43Z

‎Useful RAM-addresses

Ktwo: /* Useful RAM-addresses */

2022-07-23T09:43:43Z

‎Useful RAM-addresses

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 [[File:1-up.PNG|50px]] - Extra life. The 1-ups in the secret room of the pond and the one in the freezer are mutually exclusive. Collecting one will make the other disappear. The 1-up in the chimney is not impacted by this.<br><br>
-[[File:Cheese.PNG|50px]] - Cheese, restores 16 health (56 max)<br><br>
+[[File:Cheese.PNG|50px]] - Cheese, restores 16 health (72 max)<br><br>
 ==RNG==

@@ Line 30: / Line 30: @@
 Many games use sub-pixels to implement acceleration and inertia. Addams Family instead uses a somewhat convoluted calculation to achieve a similar result, but with some side effects that can be taken advantage of in a speedrun.<br><br>
-When Gomez takes a swim stroke (press 'A'), #$6 is added to the value in $30, up to a max of 21. $30 can be thought of as a sort of "probability momentum". Each frame, the value in $31 is subtracted by the value in $30. If $31 ends up being negative (i.e. $30>$31), #$F is added to $31 and Gomez moves one pixel in the x-direction. If $31 is still negative, another #$F is added and Gomez moves one more pixel. The value of $31 will therefore change quite erratically every frame. As a result, when looking at swimming in frame advance, Gomez moves 0-2 pixels each frame, even when the swim strokes are taken at a seemingly steady pace.<br><br>
+When Gomez takes a swim stroke (press 'A'), 6 is added to the value in $30, up to a max of 0x21. $30 can be thought of as a sort of "probability momentum". Each frame, the value in $31 is subtracted by the value in $30. If $31 ends up being negative (i.e. $30>$31), 0xF is added to $31 and Gomez moves one pixel in the x-direction. If $31 is still negative, another 0xF is added and Gomez moves one more pixel. The value of $31 will therefore change quite erratically every frame. As a result, when looking at swimming in frame advance, Gomez moves 0-2 pixels each frame, even when the swim strokes are taken at a seemingly steady pace.<br><br>
 The value of $30 can decrease in two ways (if we disregard swimming into a solid object):
 * Every time $45A changes value from 0 to 1, $30 decreases by 1. $45A is a cyclic counter that counts up every frame in the range 0-3. Hence why swim strokes need to be taken at a steady pace to maintain the speed.
-* If the d-pad is released, $30 will decrease with 1 every frame.
+* If the d-pad is released, $30 will decrease by 1 every frame.
 <br>It's also worth noting the following two important aspects about $30:
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 * Gomez can at most take a swim stroke every 9 frames. So too rapid button mashing will result in a loss of momentum.
-<br>In summary, when trying to swim quickly, there should in theory first be an acceleration phase of 5 quick strokes every 9 frames. This will increase the value in $30 5 times by a value of 6, but since $45A at the same time decreases the value 9 times (36 frames between the 1st and 5th stroke => $45A cycles through its 4 values 9 times), the final value will be #$21 if done optimally. From this point and onwards, a new stroke should be taken every 24 frames (and not faster!) to maintain the highest swim speed. Because of the layout of the pond, other considerations such as y-position and item collections obviously come into play as well.
+<br>In summary, when trying to swim quickly, there should in theory first be an acceleration phase of 5 quick strokes every 9 frames. This will increase the value in $30 5 times by a value of 6, but since $45A at the same time decreases the value 9 times (36 frames between the 1st and 5th stroke => $45A cycles through its 4 values 9 times), the final value will be 0x21 if done optimally. From this point and onwards, a new stroke should be taken every 24 frames (and not faster!) to maintain the highest swim speed. Because of the layout of the pond, other considerations such as y-position and item collections obviously come into play as well.
 ===Ice physics===
-Ice physics share the same fundamentals with swimming, but with different parameters. One is added every second frame to $30 if pressing the d-pad in the direction of movement, with a max value of 16. Movement is calculated in the same way as swimming by subtracting the value in $30 from the value in $31. The decrease of $30 from $45A when releasing the d-pad follows again the same rules as swimming.<br><br>
+Ice physics share the same fundamentals with swimming, but with different parameters. One is added every second frame to $30 if pressing the d-pad in the direction of movement, with a max value of 0x16. Movement is calculated in the same way as swimming by subtracting the value in $30 from the value in $31. The decrease of $30 from $45A when releasing the d-pad follows again the same rules as swimming.<br><br>
 Some comments:
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 ===Rowing the boat on the secret river===
-The boat shares fundamentally the same physics as ice and swimming, but with other parameters. Pressing the direction of movement and B at the same time increases the value of $30 by 4, up to a max of 27. The x-movement of a frame is again calculated by looking at $31-$30. Since the max value of $30 in this case is higher than on ice or when swimming, frames with 2 pixel movements are more common.<br><br>
+The boat shares fundamentally the same physics as ice and swimming, but with other parameters. Pressing the direction of movement and B at the same time increases the value of $30 by 4, up to a max of 0x27. The x-movement of a frame is again calculated by looking at $31-$30. Since the max value of $30 in this case is higher than on ice or when swimming, frames with 2 pixel movements are more common.<br><br>
 $45A cycles through the values 0-3 and decreases $30 by 1 every time it goes from 0 to 1 (so every 4th frame). However, this is not in effect while in the air. If linking together buffered jumps, $30 can still decrease if $45A changes to 1 on the landing frame between the two jumps. This can be avoided by holding down B on the same frame (not bufferable).<br><br>
@@ Line 108: / Line 108: @@
 A - A frame counter that cycles through the values 0-3. When changing value from 0 to 1, the value of $30 is generally decreased by 1 (for more information, see description on swimming/ice physics/rowing).<br>
 D - Gomez's movement direction<br>
-- Room number #$0-#$24. The value is only shown during room transitions, but changing while inside a room teleports to the corresponding room.<br>
+- Room number 0x0-0x24. The value is only shown during room transitions, but changing while inside a room teleports to the corresponding room.<br>
 E9/4E8 - Gomez's big/small health (72 points max)<br>
-- Timer that is 0 at the start of the game and only runs in the Toy Room. This timer is used by the game to change the smiley faces on the boxes. The exact mechanics haven't been investigated, but the conclusion is still that it does not seem possible to manipulate the timing of the smileys and that you'll always get the same pattern. Note however that the value is kept upon leaving the Toy Room. So if you for some reason would like to revisit this room, the timing of the smileys will be different.<br>
+- Timer that is 0 at the start of the game and only runs in the Toy Room. This timer is used by the game to change the smiley faces on the boxes. The exact mechanics haven't been investigated, but the conclusion is still that it does not seem possible to manipulate the timing of the smileys and that you'll always get the same pattern. Note however that the value is not reset when leaving the Toy Room. So if you for some reason would like to revisit this room, the timing of the smileys will be different.<br>
 - Contains the music manuscript when handed over to Lurch<br>
 - Contains the music manuscript in Gomez's inventory<br>

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 If turning around in the freezer, while using the inertia to continue moving, you can clip into the solid wall near the end of the room. This can be used to jump over snowballs.<br><br>
-A similar technique can be used in the bone rooms in the crypt to jump into the walls when riding the moving bone platforms. This can be used to trigger the movemnt of the upper bone platforms (they're only moving when Gomez is close enough to them) to reduce waiting time.<br><br>
+A similar technique can be used in the bone rooms in the crypt to jump into the walls when riding the moving bone platforms. This can be used to trigger the movement of the upper bone platforms (they're only moving when Gomez is close enough to them) to reduce waiting time.<br><br>
 ==Open questions==

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 ===Rowing the boat on the secret river===
-The boat shares fundamentally the same physics as ice and swimming, but with other parameters. Pressing the direction of movement and B at the same time increases the value of $30 by 4, up to a max of #$27. The x-movement of a frame is again calculated by looking at $31-$30. Since the max value of $30 in this case is higher than on ice or when swimming, frames with 2 pixel movements are more common.<br><br>
+The boat shares fundamentally the same physics as ice and swimming, but with other parameters. Pressing the direction of movement and B at the same time increases the value of $30 by 4, up to a max of 27. The x-movement of a frame is again calculated by looking at $31-$30. Since the max value of $30 in this case is higher than on ice or when swimming, frames with 2 pixel movements are more common.<br><br>
 $45A cycles through the values 0-3 and decreases $30 by 1 every time it goes from 0 to 1 (so every 4th frame). However, this is not in effect while in the air. If linking together buffered jumps, $30 can still decrease if $45A changes to 1 on the landing frame between the two jumps. This can be avoided by holding down B on the same frame (not bufferable).<br><br>
-Since the x-movement isn't decreased during jumping, a good strategy in real-time is to mash B a few times when starting to row the boat (keep in mind that the initial value of $30 is $#16) and then primarily rely on buffered jumps to avoid any slowdowns. It's then a good idea to try and press B as Gomez is about to land to either increase $30 (if its value was 23 or less during the jump) or to counter its decrease because of $45A. It requires a frame-perfect B-press for this to make any difference, but there is no downside in pressing B on the wrong frame.<br><br>
+Whether it's better to accelerate and then try to chain together a series of jumps when the x-speed is high or whether it's better to mainly stay on the gondola and row as much as possible (the game takes row inputs every second frame, so there is no risk of mashing too fast, like it was with the swim strokes in the pond) is debatable. And maybe in the end just a matter of personal preference.<br><br>
 ==Glitches and special techniques==

@@ Line 43: / Line 43: @@
 ===Ice physics===
-Ice physics share the same fundamentals with swimming, but with different parameters. One is added every second frame to $30 if pressing the d-pad in the direction of movement, with a max value of #$16. Movement is calculated in the same way as swimming by subtracting the value in $30 from the value in $31. The decrease of $30 from $45A when releasing the d-pad follows again the same rules as swimming.<br><br>
+Ice physics share the same fundamentals with swimming, but with different parameters. One is added every second frame to $30 if pressing the d-pad in the direction of movement, with a max value of 16. Movement is calculated in the same way as swimming by subtracting the value in $30 from the value in $31. The decrease of $30 from $45A when releasing the d-pad follows again the same rules as swimming.<br><br>
 Some comments:

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 <br>It's also worth noting the following two important aspects about $30:
-* Taking a swim stroke when the value of $30>=#$16 does not increase the value of $30. Once a value of 21 has been reached, the optimal swim stroke frequency is therefore every 24 frames, corresponding to the value in $30 having reduced to 15 after 6 cycles of decreases from $45A (each one taking 4 frames).
+* Taking a swim stroke when the value of $30>=16 does not increase the value of $30. Once a value of 21 has been reached, the optimal swim stroke frequency is therefore every 24 frames, corresponding to the value in $30 having reduced to 15 after 6 cycles of decreases from $45A (each one taking 4 frames).
 * Gomez can at most take a swim stroke every 9 frames. So too rapid button mashing will result in a loss of momentum.