I'm sorry, but i can't stand x86 ASM.
Each version of the compression and animation scheme i disassembled differs slightly.
You can download and browse the source of some decompression routines on my Bard's Tale page, but i can't give you more, especially on PC...
On PC, i don't know if BT1 uses the same routines as the BTCS, but the source includes everything for BTCS PC, this could help you.
Imho, by understanding how the animations are handled, you will have some hints while disassembling your version (for example, animations use XOR blitting).
Have fun with IDA