So I have some suggestions mainly adding more player support, this might be impossible but I know it would be really fun. Also, maybe you could add some weapons designed specifically for both players to benefit from. I would be really nice if you could add some other ultras for co-op only besides gun bond because most of the time, the player ultras are usually way better. Some new mutations for co-op would also be nice. That's all I got right now, thanks for reading this!

Should've read the FAQ before posting. >2P support is covered there, character-specific ultra mutations too (supported, is a command).

There are no plans to add new characters/weapons/mutations into the mod itself. Upcoming update will allow loading external graphics into the mod though.