Prince of Persia

I made a table about the background animations.
This is for the EU/US version.
(The JP version has different tile numbers for the clouds: viewtopic.php?p=17257#p17257 )

It seems that some of the animations have bugs.

Some random feedback/remarks based on what my local copy of apoplexy tells me (group values in dec):
- 2: Also used for 0x52 in marble (levels 19/27) and hallway environments. Causes the weird animation in the former.
- 3: Also used for background tile 0x82.
- 11: apoplexy does not detect that 0x5e uses this group. But, yes, it's part of an animated background... apparently.
- 18: In levels 3 and 23, 0xff also uses this group.
- 25: As you already mentioned, JP uses 0x2b-0x42. Also, in level 4, this is used by 0x57, 0x5d, 0x5e, 0x5f, 0x60, 0x61 and 0x62. Four of those are also used with other groups.
- 41: apoplexy does not detect that 0x4b uses this group.

I think there is a small confusion here.
a) My table shows what backgrounds will appear if you use a given group (with any background). -- This is not part of the level data.
b) In contrast, you investigated which tile will start which animation. -- This is stored in the level data.
That's why "apoplexy does not detect" some of them. Because it's a different thing.

If it's a bit hard to understand, here is an example:
"- 41: apoplexy does not detect that 0x4b uses this group."
Group 41 is used only on level 5, for tile 0x1B. (This is b.)
Tile 0x4B has another group, namely 44. (This is also b.)
But if you use a tile with group 41, then the game will show tiles 0x1B and 0x4B. (This is a.)

If it's still not clear, then maybe I will make a picture that explains it (hopefully) better.

No, I kind of got that - that they were two different things. However, from what I can tell there's no need for the program to specify what backgrounds will appear for each group if the program can simply loop through the tiles to see what backgrounds to show? Didn't they just make things more complicated for no reason?