I'll go with Xcom as well. After that I'd probably say Xcom, and then I really enjoyed Xcom, and then I would follow that up with a last vote for Xcom.
Actually it was kind of a down year after 2011, which I felt was very strong. I enjoyed the conclusion of the Mass Effect series, but other than that the games I was excited about rarely kept my attention for long. Faster Than Light was a neat little gem. Both Guild Wars 2 and Dishonored lost my interest faster than expected. I'll go back to them eventually, but they weren't as good as I hoped for.
So yeah, Xcom was the biggie and it didn't let me down.