.FOS File Extension
File TypeFallout 3 Saved Game
This file is saved in a binary format, which requires a specific program to read its contents.
What is a FOS file?
Saved game file created by Fallout 3, a post-nuclear war action role-playing game; contains game progress, including the player's location, character abilities, items, and mission states; can be auto-saved by the game or manually saved by the player.