Build and Shoot

Would it be possible to mod the entire game to get for example npcs? Or more weapon varieties, so that we don't need to overwrite the skins of the ones already in the game; different skins for the two teams and such, for example would be more immersive for the zombie mode...is someone already working on it?

try chameleons openspades client. it supports individual team skins.
4 npcs and shit u need to code it in urself