Microsoft is celebrating the close of 2010 by offering up to 50% off on the Best of 2010 from the Games for Windows marketplace. The sale began on January 6th and will run through January 13th 8:30 AM PST. The following LIVE-enabled titles are on sale during this time:

Batman Arkham Asylum: GOTY - $29.99/£14.99 $14.99/£7.49
Bioshock 2 - $19.99/£14.99 $9.99/£7.49
Section 8 - $19.99/£7.99 $9.99/£3.99
Blacklight: Tango Down - $14.99/£7.99 $7.49/£3.99
Osmos - $9.99/£4.99 $4.99/£2.49
Grand Theft Auto 4: Episodes From Liberty City $29.99/£19.99 $14.99/£9.99

The rest of the sale includes four games that are not LIVE-enabled, which means they have no achievements:

Age of Empires III: The Complete Collection - $39.99/£27.49 $19.99/£13.75
Borderlands (PC) - $19.99/£14.99 $9.99/£7.49
Football Manager 2011 - $39.99£29.99 $29.99/£22.49
Zuma's Revenge - $19.99/£14.99 $9.99/£7.49

Head over to the marketplace and get shopping.