Let's see here...I started the year off immersed in Skyrim on my PC. I played it to about level 54 and walked away after beating damn near every significant quest by the end of January.
After Skyrim, I let Dark Souls torture me and my PS3 through the rest of the winter. I didn't even try NG+, but with the Prepare to Die edition now available on Steam, I may buy that if it ever drops below $10.
I then jumped quickly into Castlevania: Lords of Shadow on my PS3. I liked it, especially the new take on the story (which was getting a little stale after 20+ years), but I hated the excessive QTE. That's a gaming convention that does not need to continue.
I spent all of spring playing Fallout: New Vegas on the PC. I quite liked it, especially now that the modding community has made the game so much more than it was.
UPDATE INSERTED: How could I have forgotton about my also-late foray into S.T.A.L.K.E.R.? Once I had installed the big mod package, it was a beautiful and fun game. Too bad I could never get Call of Pripyat to not crash on start-up.
I then made my first real foray into online multiplayer with Team Fortress 2 on PC. I know, 6 years late to the party, but still fun. I played the crap out of that through the summer.
I tried to get into Divinity 2 on my PC, but I just can't seem to stay interested very long. It's on my must-finish list for 2013.
Then Mass Effect 3 went on sale in late September through Amazon download (take that Origin!). In particular, the multiplayer, in which I have played over 800 games and am now in the top 5% by any metric. I'm trying to ween myself off with a bucket list game, Clive Barker's Undying, which is great but the Firebases, they call to me. Even now...