This format predates Sonic X for the Leapster and works entirely differently from what I can tell (and might have some form of compression for the image data?). There aren't any palettes in the file that has them in it. The attached zip file contains both the file that has the sprites in it and a file I got out of it that I'd assume is a sprite (both from Counting on Zero). The same format appears to be used in Cars, Cars Supercharged and Nascar as well.
SpriteData.zip

Update:
The data I shared isn't sprite data. I figured out that the tiles are actually in the DPAK section with the ID 3 but are compressed using some custom "LZB" and "LZW" compression (this info was obtained using another Torus game on the LeapFrog Didj known as Didji Racing: Tiki Tropics. That one has debug symbols intact.)

Here are some sample files (I couldn't find any LZW ones in the data, but there's a ton of LZB-compressed data):
LZB.zip

 

The names of the functions I found that handle these if anyone looks into this:
- TSEUnpack_GetType
- TSEUnpack_Lzb
- TSEMemcpy (also used in that function)

Edited September 1, 20241 yr by Blingus

I figured out the format and have documented the compression here:
Torus Games (Leapster) sprite decompression documentation

 

Edit:
Fixed the link

Edited July 12, 2025Jul 12 by Blingus