Dragon's Dogma and Sleeping Dogs were both stand-out original games in what has been a very sequel-heavy year. I've just bought Dishonoured today (because my local GAME had the special edition with the tarot cards for £29.99), so I'll have to see how that stacks up.
I've really enjoyed Borderlands 2, the first DLC was meh, but the main game is really compulsive. It has its problems but it's the game I've played the longest this year.
My biggest disappointment was Darksiders 2. Limp, half-empty and there was barely any story at all. It could have been so much better and the latest DLC is around half an hour long making the season pass a gigantic rip-off.
The less said about Mass Effect 3, the better. BioWare definitely aren't on my Christmas card list.