Well the end of the year is coming and I usually make this thread around this time: What games have you beat? List which system and any other details you want to share. Here's mine and I'll update it as I get through my pending list:

NES:

Mario 3
Contra
Castlevania 2

SNES:

Castlevania IV
Super Mario World

PS1:

Castlevania: Cronicles
Castlevania: Symphony of the Night (206% completed)

Wii:

New Super Mario Bros

PS3:

Infamous 2 (good ending, found all shards, evil ending pending as well as platinum trophy)
God of War II
Prince of Persia: Sands of Time
Mortal Kombat (still think it has the best story mode in a fighting game)
Portal 2
Lego Harry Potter 1 (got the platinum trophy for it)
Uncharted 2 (hard playthrough)

360:

Call of Duty: Black Ops
Dead Space 2
Dragon Age: Origins
Dragon Age II
LA Noire (100% all cases, got all the game's achievements but not DLC... which pisses me off as the game doesn't appear on my completed game list because of it)
Deus Ex: Human Revolution (completed once on normal and once on hard)
Batman: Arkham City (Main story, side missions, all riddles/trophies found, all combat challenges completed for Batman, Game Plus playthrough pending)
Split/Second
Modern Warfare 3 (veteran playthrough pending)
Lego Pirates of the Caribbean (just a few small achievements left to get 1000)
Castle Crashers (must have beaten it 30 times this year at least)
Scott Pilgrem
Shadows of the Damned
Bulletstorm
Vanquish
Xmen Arcade (how could I forget!)
Xmen Destiny

PC:

Deathspank (100% completed everything, including Steam achievements)

Pending:

Battlefield 3 (360)
Alpha Protocol (PS3)
Resident Evil 4 (360)
Outland (360)
Costume Quest (360)
Turok (PS3)
A Link to the Past (SNES)
Super Metroid (SNES)
Dead Island (360)
Rayman: Origins (360 and buy this game!!)
Lego Indiana Jones (360, pending 100% completion)
Enslaved (360)
Fallout: New Vegas (360)
Half Life 2 (360)
Fable 3 (360)
Deathspank: Things of Virtue (PC)
Starcraft 2 (PC)
The Witcher (PC)
Just Cause 2 (PC, altough it's more of a game I play to blow shit up, not complete)
Borderlands (PC)

hmm, my list is short this year. I'm sure I'm missing some or there may be some overlap with last year but here we go:

NES:
Legend of Zelda (I do pretty much every year)
All six Mega Mans
Space Shuttle Project
River City Ransom
Platoon.... many times over

SNES
Earthbound
Super Mario RPG

N64
Harvest Moon
Jet Force Gemini
Glover
Ocarina of Time
Majora's Mask

Gamecube
Paper Mario: Thousand Year Door
Alien Hominid
Chibi Robo
Ocarina of Time Master Quest

GBA
Mario & Luigi Superstar Saga
Metroid Fusion & Zero Mission
Warioware Twisted
All the Mario Advanced games

PS
Crash Bandicoot

PS3
Uncharted 3
Undead Nightmare
Portal 2
L.A. Noire

I really haven't had that much time to play games this year :\

But, I beat:

Super Mario Sunshine
Super Mario 3D Land
Golden Axe
Portal (again)
Portal 2 (twice)
Uncharted (Hard)

... I can't ... remember others. I'm sure there's more, I just can't think of them. I actually have a lot of games that are like ... at the end, but I haven't actually finished them yet :\

Fixed! Damn I nearly forgot!!

Do you mean beat this year or is is a cumulative list of games we've finished overall?

Just this year:

PS3
Back to the Future (all 5 episodes)
Batman Arkham Asylum (second play through to collect all of the Riddler puzzles)
Batman Arkham City (main story, new game +, all riddler trophies, all cases closed, all characters found, some challenge maps)
Catherine
Dead Nation (Three times with my gf, once with a friend)
Marvel vs Capcom 3
Metal Gear Sold 4 (finished a playthrough I must have started last year to get the stealth camo)
Mortal Kombat (more fighting games need story modes like this)
Portal 2
UFC Undisputed 2010 (finally finished career mode after putting it off for so long)

PS2
Champions of Norath (first time I ever beat it. Played through the whole story with my gf)

360
Dead Rising 2 co-op
Mass Effect 2 (completed on insanity and unlocked all achievements)
Shadows of the Damned (finished every difficulty level, unlocked all achievements)
Plants vs Zombies
Red Dead Redemption Undead Nightmare
Resident Evil 5 (went through the co-op with gf on professional)
X-men The Arcade Game (god knows how many times now lol)

PS1
Resident Evil (just felt like going through Chris' story again)

Wii
Resident Evil the Umbrella Chronicles (co-op with my gf)

iPhone
Army of Darkness Defense
Plants vs Zombies


There might have been more, but that's all I can remember that I played all the way through this year.

YES!

Been a pretty slow gaming year for me.

PC:
Borderlands
Portal 2 (coop and single player)
Back to the Future
Puzzle Agent 2
Dead Island
Blocks that Matter

PS3:
Assassin's Creed: Brotherhood
Castle Crashers
La Noire
Batman Arkham City
Uncharted 3: Drake's Deception

iPhone:
Infinity Blade
Puzzle Quest 2
Swords & Sworcery
Tower Defense: Lost Earth
Hector: Badge of Carnage ep2
Scribblenauts Remixed

DS:
Last Window: The Secret of Cape West
Clash of Heroes
Professor Layton and the Unwound Future

Wii:
Donkey Kong Country Returns


In progress:

PC:
Cogs

Wii:
Skyward Sword

iPhone:
Broken Sword 2
Infinity Blade II (as soon as it's released tomorrow)

Oh, I forgot about Borderlands and Costume Quest! I finished those up too.

I wanna gay marry Tim Schafer. I need to get back to that game and beat it. I bought it when the Awesome Video Game guys were playing it on their live show but I just didn't end up beating it.

I have trouble finishing...

It's really good. It's kinda short though!

I think I might play it every year. Play Costume Quest during halloween and gubbins on ice after thanksgiving. It's one of the best holiday themed games I've ever played. Perfectly captures the spirit of Halloween ... well ... for me. I don't know about some crazy foreigners

Probably my biggest list, though the majority are really short:

Games I already beat, but beat again this year:
Scott Pilgrim vs the World- beat it with Ramona; now I just need to beat it with Knives and Nega Scott and the game's beat with all 6 characters (man, I love this game)
Resident Evil 5- finished the last hour of the game on my second playthrough that I held off last year
X-Men Arcade


Games I beat for the first time:
Resident Evil 2- A/B scenario, which I was told was the non canon scenario, RIGHT after I beat the game.
Kirby's Epic Yarn- was in the last areas in 2010. Just had to finish it off
Uncharted 1- Amazing
Uncharted 2- Holy crap
Sonic the Hedgehog
Sonic the Hedgehog 2- finally finished my favorite Sonic game
Okami- Loved this game. I need to play it again
Streets of Rage 2
flower-awesome
Hard Corps Uprising- beat it with Krystal. Will start my Bahamut playthrough soon
Turok 2: Seeds of Evil- huge disappointment. It would have been amazing as just an FPS if it didn't take 200 hours to go from point a to point b. It was just a giant scavenger hunt with amazing guns and shooting.
Dead Nation- bleh
LittleBigPlanet- awesome, but just plain cruel in the last levels

Backlog (3 games left until it's complete (2 games are now added since 2010):
Jet Force Gemini- I just need to sit down and play through this one day
Chrono Trigger- I take eons to finish RPGs. And the worst part is when I sit down to play it, I forget what I have to do and wander until I quit. Need to beat this game. It's so great.
Resident Evil 3- Got to the part with the trolley filled with the men with fake accents and Jill gives her billionth speech on how Umbrella is evil. I still can't fathom her stupidity in the game.
Pursuit Force- Just need to sit down and finish off the last gangs. It's kinda hard.

Who wouldn't?

I love Tim's games, and I've been meaning to pick up Stacking and Costume Quest for a while. But I feel I got a bit burned on Brütal Legend. I loved the character's and atmosphere of the game. But who the hell markets an RTS as a hack 'n' slash? It's the sole reason I haven't rushed out to pick up his later games.

To be fair, Costume Quest and Stacking aren't actually Tim Schafer games. Tasha Harris was project lead on Costume Quest and Lee Petty was the lead for Stacking. Schafer's involvement wasn't in the project lead capacity for either of the games (though he helped creatively. I know a decent amount of dialog in Costume Quest was Schafer's).

Yeah I know. But I tend to think of everything that comes out of Double Fine as a Tim Schafer game. It's not that big of a studio after all.

No, I understand. He's the public face of studio, everyone just talks like all their games are his. But, it's pretty unfair to the other designers there. It's a common occurrence, I was just pointing out they're not actually "Schafer games" in the traditional sense of, "thought up, directed by, and designed by"

Update:
Finished Bad Company 2.

You're absolutely right. I should've probably given them the cred they deserved.

Bad Company 2. Shortest goddamn campaign ever, right?

I think it just felt that way. Realistically it only took about 6 hours ... but MGS 1 was less time than that and it felt more fulfilling as a campaign .. so maybe that's it?

I also thought Mario Galaxy 1 was too short ... then I saw I spent 30 hours on it and went ... oh ... it's perception! Yay!

XBox 360:

Modern Warfare 3
Borderlands (For the 3rd time)
Quake Arena Arcade
Dead Island
Costume Quest
Torchlight
Ilomilo
X-Men Arcade
Hydro Thunder
Super Meat Boy (Well...I beat it, but I didn't get 100% of everything.)
Dead Rising 2
Dead Rising 2: Case West
L.A. Noire
Portal 2
Earthworm Jim HD
Halo Reach
Turtles In Time Remake

XBox Live Indie Games:

Total Miner
DLC Quest
Crossfire 2
Inferno
Lootfest
Epic Dungeon


And games in progress...

Skyrim
Batman: Arkham City
Puzzle Quest 2
Outland
Wizorb

Minecraft