I`m always on the lookout for new formats to add to my general code.
Usually I will need a selection of example files to look out so I can see if I can decode the format. Often you will find the actual format is something more well known. Many supposedly custom game formats turn out to be standard DDS in a custom wrapper or with extra data included. Even where the format is truly custom it will usually store the actual image data in standard 16 bit, 32 bit or DXT.

If you have a few files you could send me (or point me at on the web) I can take a look