
Bethesda released a free version of The Elder Scrolls II: Daggerfall -- their 1996 title that served as the foundation for their future open-world RPG titles like The Elder Scrolls IV: Morrowind.
Download Daggerfall II now (148MB)
View installation instructions for Daggerfall II (includes some legal stuff)
Note that you'll need the DOSBox emulator to run the game, as it hasn't been updated to run on modern operating systems.