.GMBCK File Extension
File TypeGame Maker Background Image File
What is a GMBCK file?
Graphic file used by games created with GameMaker, a game development IDE published by YoYo Games; contains a collection of images that can be tiled in the background of a game scene; also stores the background's name and target image size.
GMBCK files are used by GameMaker for auto-generating in-game textures; they may be created and saved using the Background Properties window in GameMaker.