I can definitely think of a few I played this year (though they may have been published earlier).

Rogue Legacy
Hotline Miami
Botanicula
Stealth Bastard
Duke Nukem 3D: Megaton Edition

It's been a great year for linux gaming :)

Does this have to be this years releases? Because I have actually not played that many "new" games in that case, as I am still glued to many old favourites, have a considerable gaming backlog, and had my main gaming rig down for almost all of the summer. :|

The best "new" game I played this year was probably Trine 2: Complete Story, if you count that as being a new release. The most surprising "new" game I played was Jedi Knight II: Jedi Outcast, if you count the source code release as making it new. About the only strictly "new" content I have played is the "Hard Times" DLC for Rochard and a little bit of Spooky Range.

I have purchased a lot more games than I have played this year though, including the Humble Double Fine Bundle, Humble Indie Bundle 9, Faster Than Light, Dungeons of Dredmor Complete Pack, Paranautical Activity, Inverto, Livalink, and the first two chapters of Doorways. I also purchased the Desura release of Penumbra Collection, which I am currently in the process of slogging through for reasons which may fairly soon become apparent. ^_^

Quoting: Quote from HamishI have purchased a lot more games than I have played this year though...

Well I can certainly relate to that! Who'd have thought we'd have so much going on with Linux gaming :D

Sir, You Are Being Hunted
Metro: Last Light
Little Inferno
Tiny & Big: Grandpa's Leftovers
Left 4 Dead 2

It was fun to play all the Half-Life 2 stuff again.

I've played a ton of stuff this year, but it's been Killing Floor's release that's kept me out of Windows. In fact, because I haven't logged into my Windows partition since early August, I've pretty much wasted a £70 subscription to Planetside 2...

Ah well. KF has kept me busy when I'm not playing all these new releases:
Delver (which is awesome!)
Metro: Last Light
PixelJunk Shooter
Anna
Shadowrun Returns
Painkiller
Mark of the Ninja
Natural Selection II
Teleglitch
Fez
Dota2
Sir you are being hunted

Honestly, the list goes on and on. Monaco, Game Dev Story, Rogue Legacy, Kairo, Prison Architect, Battle Worlds Kronos, Thomas Was Alone, The Cave,

I've hardly scratched the surface of some of these titles. Too many to play properly!

For me it was:

- Half Life 2 Deathmatch <3
- The Raven
- Painkiller
- Eldritch
- Delver
- Sir you are being hunted
- Duke Nukem 3D: Megaton Edition

I probably forgot a ton of other titles :)

I've bought more games then played, Unfortunatly quite a few of those I kinda regret buying since I didn't like them as much as I though they where.
The games that I did play are a bit older.

So this is the list I could come up with;

• Minecraft


• half-life 2


• garrysmod


• Left4dead 2

Started going through Realm of the Diggle Gods last night while utilizing some of the skills present from the other two DLCs. Meh, they still are new to me. :P

This is quite a hard one. A year is quite a span of time :D

• Team Fortress 2


• Killing Floor


• Left 4 Dead 2 (I know, valve fanboy)


• Deus Ex  Not native :(


• Xonotic


• Dota 2


• Awesomenauts

Honorable mention: Super Hexagon (amazing soundtrack and just addictive enough to keep me going for a few weeks)

Wow it´s hard to choose. I´ve bought 86 native linux games this year (and it´s not over yet.) 

But those I´ve played the most, and had the best time with is:

Metro: Last light
Euro Truck Simulator 2
Mark of the ninja
Game Dev Tycoon
Football Manager 2014
Surgeon Simulator 
Brútal Legend

• Dota2 - Even though it makes me angry


• Mark of the ninja - still need to finish it oops


• Planetary Annihilation


• Pandora


• Metro: LL

Portal!

I guess Portal 2 is coming next year with the Steam boxes, right???

Also really liked Stacking and Dungeon of Elements, finished both of those.

Might manage to get into Planetary Annihilation in 2013 since there's still a month left, but also going to be super busy at work (Christmas vacation = single day off on Dec 25?) so it might get pushed into 2014 list.

• StarMade, multiplayer sandbox roleplay space-shooter game, still alpha but very stable


• Left 4 Dead 2, Co-op shoter, sadly too much griefer and frontrunner on the server


• Crusader Kings II, extremely deep strategy

2014 Year of the awesome RPG Linux titles, or so I hope

Mine are:

Metro LL (after I got it working)
Sir you are being hunted.
FORCED (Great 4 player co-op)
Kerbal Space Program
Left 4 Dead 2 

Honorable mention:

The plane simulator/ world war 2 game who's name I cannot recall. The only reason it's not on my list is because the game Configurator doesn't launch, which means I can't change any graphical settings (stuck at like 1366x768). It's broken and therefore unplayable in my books. 

Quoting: Quote from jegmancsBrütal Legend: saw the trailer and the reviews when it came out, and I hoped that one day I can play it on Linux. i don't like heavy metal, but this game has a unique feel and Jack Black. i am still at the beginning and I am waiting for my gamepad to arrive.

Not that I have played my copy yet, but I would have thought not liking Heavy Metal would have been strongly detrimental to this title?