Does this include games that were released late last year? Like Christmas time?
If so I'd say Wrath of the Lich King for sheer massive amount of gameplay. But single player would be Resistance 2.
But if not... well I think this year probably has the very least video games played by me in my entire life. The only games that I bought that were strictly released in 2009 would be Ghostbusters for PS3 and Dragon Age: Origins and the very disappointing Resistance Retribution for PSP.
My inner gaming child is probably crying right now, but that little bastard never had to work for a living and pay for his video games!