Fenixp: I have played a lot of awesome games this year, but... Dishonored + its DLC. Finished the original 3 times, the DLC storyline 2 times. Put over 50 hours into the game. I just love it.
I was so very tempted to get this in the sales, but I have the feeling my brother may have picked up the PS3 version as a christmas gift and I don't think my PC would do it justice anyway. One way or another it's on my list of games to pick up.
arr0whead: Ys Origin. After finishing it using the keyboard, I even bought a gamepad so I could play it properly.
This would be a real contender for me too if I hadn't been so blown away by Vampire: The Masquerade - Bloodlines, I've sunk a lot of hours into it. Great game.