The file extension is a proprietary archive format developed by Ubisoft . It acts as a "container" file (similar to .zip or .pak , but heavily encrypted and structured differently).

Because datapc.forge is a core archive, if even one byte of data is corrupted (due to a bad mod install or hard drive error), the game will crash on startup.

Tools like the AnvilToolkit allow users to unpack the .forge archives into readable files.

Always back up your original DataPC.forge file before attempting any manual modding. Most modern mod managers will do this for you, but a manual copy is the safest insurance against a full game re-installation.