Forza Motorsport 5, Styx, GTA V, and GTA IV are on offer.
On Xbox One the offers include Max: The Curse of Brotherhood (which you should already have, if you picked it up in the Games with Gold offer last year), Styx: Master of Shadows, and Forza 5.
The Xbox 360 deals are mostly about Grand Theft Auto, with GTA V, GTA IV, and GTA: San Andreas with over 67% off across each of the games.
The full listing of discounted games and add-ons are below, available for both Xbox 360 and Xbox One consoles from today through 12th January. Or you can check them out on Major Nelson’s blog too:
Zoo Tycoon 50%
GTA V 67%
GTA IV 75%
GTA: San Andreas 75%