Is Football manager 2013, which probably speaks a lot to the general quality of games this year but man, I frickin love Football manager.
It is my civ, the type of game you go "just one more game" and boom you are finding yourself still playing it at 5 in the morning, and no game this year has had me more invested than this game, the adrenaline rushing when you are holding on to a lead with 10 minutes left knowing full well that all you can really do is pray, the exhilaration when you succeed, Scouting and developing new players, it is just endless amounts of fun.
Now what makes FM 2013 better than FM2012 you might ask (you probably aren't though), and well it cleans up the interface and has a lot of smart improvements and it just seems more stable than 2012 which crashed on me kind of a lot.
They also streamlined and improved a lot of stuff like the training system, added the possibility of hiring a DoF which is a godsend as you can finally get someone else to renew contracts as there is literally nothing worse than offering new contracts to 30 people at the same time.
Anyway, FM 2013 was the most fun I've had with games this year, partly because I feel I may be falling out of love with the medium and partially because.. Well it's awesome.