If it was exclusively released in 2012 and I hadn't played it on the PC, I'd go for Witcher 2.
What else came out this year?
I've mostly been catching up on games. Probably the most fun has been InFamous 1 & 2, back to back. But I just played those this year (I started InFamous in 2009, but didn't finish 'til 2012), they weren't released.
Wow. I'm wondering if Witcher 2 on the 360 is the only 2012 game I've played? I want to say Journey, but I think that was 2011. So I guess I'll just have to say InFamous 1 & 2 back to back.