QuArK

QuArK stands for Quake Army Knife and is a game editor for Quake and many other games using engines similar or compatible with id Software's engines used by Quake games. QuArK currently supports 41 distinct games, 5 generic game engines, and a countless number of expansions packs, addons, and mods. It can edit maps and models, import sounds and textures, run compilers, and is able to create and modify .pak and .pk3 files, as well as importing compiled .bsp files in order to add/change/delete entities from these files. No other game editing tool available has the ability to do all of these things.