My starting point was this excellent thread, where people discovered that
- background images are packed in VIGNET.DAT, and
- at least one of them are encoded in PCX format.
Pondering upon this observation for a couple of hours, I realized that VIGNET.DAT indeed consists of PCX files in a bit of twisted way: each file is encoded by XOR operation.
I am still working to figure out which byte should be used for the encryption (because the key byte is different for each image), but at least we know how to decode them manually. Here are some ripped images:
Now the point is that, since we are beginning to understand how images are packed in, we will be able to modify them as well. Probably this is a good news for those who want to make a fangame.