Thinking back to major titles released in 2010...
At Release:
Elemental: F, but awesome in the way that a trainwreck in slow motion is awesome - easily worth the money in entertainment value, just not as intended.
Starcraft 2: A, the distillation of traditional RTS gameplay with some remarkably good single-player campaign design.
CiV: B, some crucial innovation, but some technical issues emerge surrounding DLC and succession games.
Battlefield: Bad Company 2: A+, whoa, gorgeous graphics and the best sound design ever made for an FPS. (it seems odd to include an FPS game in this discussion, but it's a piece of context)
S.T.A.L.K.E.R.: Call of Pripyat: A+, doesn't recapture the meaningful story of the original, but is so much better in technical terms. A fantastic RPG mixing exploration with an ultimate linear goal.
End of 2010:
Elemental: F, now it's just bad; at this point the many remaining bugs and persistent hideous balance issues are tiresome rather than hilarious. Worn out it's welcome, and rarely if ever touched.
Starcraft 2: A, yet I'm not playing it anymore. It's still an amazingly deep game, but it's just too demanding to keep up with.
CiV: C, long since uninstalled after it's exceptionally shallow nature (courtesy of the terrible tactical AI and a one-dimensional optimal strategy) is played out. Has mod potential.
Battlefield: Bad Company 2: A, despite having mastered the basic flow of an information-based team FPS (dynamics caused by destructible terrain and team-wide 3D spotting), I'm still learning nuances of how different weapons handle given the ballistic system - and uncovering new playstyles each time! The lack of mod tools means that even the variation provided by destructible environments begins to wear thin after a couple hundred hours of playtime though.
S.T.A.L.K.E.R.: Call of Pripyat: A+, mods push this game over the top; not only can it be tweaked to be one of the most unforgiving survival-action RPGs around, but it also becomes one of the most beautiful games in existence when the engine's potential is unleashed by modders.
Now:
Elemental: D, it doesn't seem to explode in my face much anymore, and some of the very worst imbalances are being toned down, but there's still basically no compelling reason to play given the blandness. Waiting for Fallen Enchantress.
Starcraft 2: A, but I'm still not playing it. I'm now tinkering with the more casual Dawn of War II: Retribution multiplayer.
CiV: C, the upcoming balance patch sounds interesting mechanically, but I doubt that they'll ever address the tactical ability of the AI.
Battlefield: Bad Company 2: A, finally mastering the VSS after it's different ballistic qualities made me initially dismiss it. Still wishing there were more maps, but I'm not likely to stop playing any time soon. New tactics spring to mind every time I dive into the game data, even though I've already logged over 400 hours online since the multiplayer beta began.
S.T.A.L.K.E.R.: Call of Pripyat: A+, I'm now on my third playthrough of the game, which is my second modded playthrough, and I'm still discovering new things whenever I take the time to wander. One of my favorite action-RPGs of all time.
Basically, it all boils down to a mixture of casual-ness and depth. I want to keep discovering new things about each game (disqualifying CiV and eventually Elemental), but I also hate feeling like professional study is required to win (disqualifying Starcraft 2). Of games that were released in 2010, Bad Company 2 and Call of Pripyat are the only games that I feel compelled to return to.
