FF Viewer is a community-developed utility designed to decompile and view the contents of proprietary .ff files. While developers like did not intend for these files to be modified, the modding community uses FF Viewer to:

Mira rubbed her eyes. She was a digital archivist, a keeper of forgotten things. For the last six months, she’d been trying to decode a corrupted file labeled — a file so broken that every standard video player crashed the moment it touched the metadata.