What is a GMBCK file?
YoYo Games has developed the GMBCK or Game Maker Background Image File to help it in auto-generating the in-game textures. It contains a collection of images that the company can use as the background for its game scenarios. It also saves the background’s name and target image size to make it easier for your future reference.
You can create these files by using the Background Properties option in the GameMaker software.
How to Open GMBCK Files
How to Make GMBCK Files
Exact steps for creating GMBCK files will vary by program and operating system. Download one of the above listed programs and you should be able to follow typical procedure for opening files or creating files from the File menu. Typically you will select File > Open or File > New and continue through the prompts. Some programs may follow a different procedure for either creation or opening of files.