A ( .pk4 ) is the archive format utilized by the idTech 4 engine—the engine powering Doom 3 , Quake 4 , and Prey (2006). Similar to the .pk3 files in Quake III Arena , the .pk4 format is essentially a standard ZIP archive with a renamed extension.
Original uncompressed assets for Doom 3 totaled roughly 3.6GB, which was packed down to 1.44GB for the retail release. doom 3 pk4 files
: Holds high-resolution textures and graphical materials. doom 3 pk4 files