Hmm, tough question, since I can hardly remember what came out in early 2010. I'd probably throw out a list like this:
1. FO:NV
2. Mass Effect 2
3. Alpha Protocol
4. Risen (I bought it this year, might be a 2009er)
5. Civ 5
6. MLB 10 The Show
7. Red Dead Redemption
8. Gran Turismo 5
9. Just Cause 2
That's about it, pretty good year. I'm never going to really understand all the flak AP took, I had a blast playing it. Other than Civ 5, it's also the most replayable of the bunch, it is rare that an RPG gets me playing it more than once. The only other real surprise was Just Cause 2, that game was a better sandbox title than RDR for me, just didn't have the same story.