PSK file extension is used by files related to Unreal Engine game development environment. Unreal game engine imports information regarding mesh data for 3D models from PSK files. PSK files are usually utilized along with PSA files, which include 3D model animation data.

Unreal Engine, and by extension PSK file format, is very popular among FPS game developers. Until now, about 250 game titles were created using Unreal Engine.