The 2007 Game of the Year is Super Mario Galaxy.
The runner up is Portal.
The master thread for all of these contests can be found here.

Welcome to the latter part of the 2000’s, which may be the most interesting time in the history of gaming.  It was so interesting that someone created a website in 2006 focusing on the video game sales during this time in gaming.  But what was it that made the late 2000’s so interesting?

The PS2 dominated the home console space so thoroughly that it seemed like Sony had a permanent monopoly on gaming.  Not only was the PS2 the best-selling system of all time, but it also forced Sega out of console gaming and into a role as third party publisher.  Nintendo, the former king of home consoles, was in third place with the GameCube relying mostly on their handheld systems to make a profit.  And with the solid launch of the PSP in 2004, it seemed like Nintendo couldn’t even rely on their handhelds anymore. 

Enter Satoru Iwata, Nintendo CEO and black-belt in business jiu-jitsu.  Instead of Nintendo launching powerful systems to compete directly, Iwata treated his competitor’s power as a disadvantage and used it against them.  That move to high definition, especially, increased costs and slowed development times.  So, Nintendo focused on new control methods for the Wii and DS and kept these systems as weaker than their competitors.  This meant that Nintendo could keep development costs down and continue to release new games at a good pace.  Even with major third-party developers supporting Sony and Microsoft, Nintendo turned everything around.  Somehow, they were competing with almost the entire game industry and winning.

Here is the tl;dr version of the above:

Playstation: “I am inevitable.”
Iwata: “And I am Iron Man.”

As for 2007 specifically, Generation 7 had fully started.  Sony was trying out new content for its first-party games, while Microsoft and Nintendo were putting out sequels to some of their biggest franchises.  Third-party publishers were also starting to release some high-profile games, and the PS2 simply refused to die.  “Hello? PS2?  Read your emails.  Generation 6 is supposed to be over.“  So, without further ado, here is the list of games for 2007:

Portal (PC)
This puzzle FPS is more about opening time-space portals instead of killing stuff.  Follow the instructions of a “benevolent” AI and enjoy some cake while playing this Valve classic from designer Kim Swift.

"Still Alive":  https://www.youtube.com/watch?v=dxTNqYAWISs

God of War II (PS2)
Even in 2007 the PS2 continued to get high profile games like this second entry in the God of War series.  God of War II would sell over 4.2 million copies and it scored a 93 on Metacritic.

Halo 3 (XBox 360)
The XBox 360 got its first entry in Microsoft’s flagship franchise in 2007.  Halo 3 scored a 94 on Metacritic and sold over 14.5 million copies. 

Bioshock (XBox 360/PC)
Go underwater to discover Ayn Rand’s wet dream in the city of Rapture.  PS3 owners had to wait an extra year to enjoy what XBox 360 and PC owners were raving about in 2007.  Bioshock scored an impressive 96 on Metacritic and sold over 4 million copies.  Would you kindly consider voting for this game?

Call of Duty 4: Modern Warfare (XBox 360/PS3/PC)
For whatever reason, the developers behind this series decided to move away from a WWII setting and they used a more modern setting instead.  This ended up being a really good idea.  Call of Duty 4 scored a 94 on Metacritic and had sold almost 16 million copies as of 2013.

Rock Band (XBox 360/PS3/PS2)
In a strange twist of fate, Harmonix got shut out of making future Guitar Hero games.  They responded by launching this brand-new series which allows up to 4 players to simulate their own rock band using guitar, bass, singer, and drums.  Rock Band would sell over 4 million copies and scored a 92 on Metacritic.

Uncharted: Drake’s Fortune (PS3)
Naughty Dog started their iconic series back in the early days of the PS3.  This first Uncharted game would sell over 4.8 million copies.

Metroid Prime 3: Corruption (Wii)
The Wii got the third entry in the Metroid Prime series.  Metroid Prime would sell over 1.4 million copies.

Super Mario Galaxy (Wii)
Meet Princess Rosalina and Luma for the first time when Mario launches into outer space.  This gravity defying 3D platformer would score a 97 on Metacritic and sell over 12.8 million copies.

Other (please specify)
If you think another game deserves to be "Game of the Year" other than one of the 9 I listed above, then please vote “Other” and say your game in the comments.  If the "Other" category takes at least 2nd place and no other game gets at least 40% of the vote, then I will do a runoff vote including the most mentioned game(s) from the comments.

Voting for 2007 Game of the Year will end on Monday, Nov 13 at 11:59 PM, EST.

Here are some clarifications that I’ve stated in earlier threads, but people may have missed or forgotten.

A) You cannot vote for game compilations. That means you cannot vote for The Orange Box this year or Metroid Prime: Trilogy in 2009.  You can, however, vote for Portal, Team Fortress 2 or Metroid Prime 3 this year, since those are all individual games.

B) The only chance you have to vote for any given game is its earliest release date. That means if you prefer the PS3 version of Bioshock or the Wii version of Rock Band, this is still the year to vote for those games, even if your specific version released in a later year. 

Anyway, here are some other notable games for 2007:

Tekken 6 (Arcade)
Guitar Hero III (PS2/PS3/XBox 360/Wii/PC/Mac)
Odin Sphere (PS2)
Crisis Core: Final Fantasy VII (PSP)
Monster Hunter Freedom 2 (PSP)
Patapon (PSP)
Ratchet and Clank: Size Matters (PSP)
Syphon Filter: Logan’s Shadow (PSP)
Wipeout Pulse (PSP)
Mario Party DS (DS)
The Legend of Zelda: Phantom Hourglass (DS)
Pokemon Mystery Dungeon: Explorers of Time/Darkness (DS)
Professor Layton and the Curious Village (DS)
Professor Layton and the Diabolical Box (DS)
The World Ends With You (DS)
Crackdown (XBox 360)
Forza Motorsport 2 (XBox 360)
Lost Odyssey (XBox 360)
Mass Effect (XBox 360)
Assassin’s Creed (PS3/XBox 360)
Tom Clancy’s Ghost Recon Advanced Warfighter 2 (PS3/XBox 360/PC/PSP)
Heavenly Sword (PS3)
Pixeljunk Monsters (PS3)
Ratchet and Clank Future: Tools of Destruction (PS3)
Super Stardust HD (PS3)
Link’s Crossbow Training (Wii)
Mario Party 8 (Wii)
Mario and Sonic at the Olympic Games (Wii)
Super Paper Mario (Wii)
Wii Fit (Wii)
Zack and Wiki (Wii)

Rock Band was so good

Great, great year. BioShock for me, followed closely by Super Mario Galaxy.

BioShock is a triumph. Amazing storytelling. Some of the best production design ever in a video game. Tons of room for player choice. And riveting action-adventure-RPG gameplay. It’s burned into my memory. And it’s one of the few games to totally break me down and make me cry at the end.

What can I say about Super Mario Galaxy. Just an endless procession of surprises, inventions, twists, and curiosities, set against a wistful story and an all-time great OST.

This was an incredible year, one of the all time greats for gaming. So many fantastic titles, many of which would be worthy games of the year in a different year. It really was an amazing time to be a gamer.

The top honour however has to go to Super Mario Galaxy.

It's as if the devs managed to capture and crystallize the joy of childhood play and print it onto a disc; that same feeling of exploring playgrounds or going deep space adventures in the backyard, powered only by our imagination. Just moving around or toying with the game's gravity mechanics is a pleasure, backed up by wildly creative level design, a sublime soundtrack, vibrant visuals, and a sumputous atmosphere.

We may never be able to truly relive our childhood, but for me at least, Mario Galaxy gave me a chance to revisit it in a virtual world of endless wonder.

Wasn't sure what to pick until I noticed a certain game in the other-list. Still, I could mention a few honorable mentions.

The first Uncharted was a good game, but lacking in several areas that made the following titles in the series truly great. The gameplay in particular was still quite unpolished. Bioshock also deserves a mention, but I didn't play the game for the first time until, and a lot of the impact the game initially had was lost since I was very well aware of the big twist. Still a great game, but the solid gameplay and good writing aren't quite enough without the added shock that the big moment had back in 2007. Crisis Core is the best game on the PSP, but not quite on par with the best games of the year in general. The story is very good, and the added background to some of the minor characters of FFVII is great, with a wonderfully emotional final chapter, but the limits of the hardware and the repetitive gameplay holds it back. Finally, Portal was for a very long time my favourite game from 2007. Genuinely one of the very best puzzle games of all time, with a near perfect villain to boot. 

Yet, the game I will vote for, is Lost Odyssey. Effectively a Final Fantasy in all but name, at the time of its release it was well-received, but also somewhat maligned for what some people perceived as outdated gameplay. These people are wrong. The gameplay is great, the characters and story are very good, in particular the stories that detail past events in the characters' lives are wonderful, and the music is excellent. The one real drawback the game has is its long load times, and that's a minor grievance at best. I doubt it'll win the vote, but as far as I'm concerned, it's better than any other game released in 2007. Of the ones I've played at least.

I remember COD4 being my GOTY, but I knew at the time that Super Mario Galaxy would be the one I would love more with time. COD4 is great, but its not something I care much about now. SMG is still a masterpiece.

My vote is for STALKER Shadow of Chernobyl. Wasn’t really anything like it at the time and there still isn’t much like it. Rock Band is just as worthy a winner though, with equal credit to the game and those gaming parties.
3. Final Fantasy Tactics A2
4. Halo 3
5. Bioshock
6. Assassin’s Creed

I love God of War II, but the title must go to Modern Warfare. It was a incredible game. Still is. Hard to believe it's 16 years old already.

Lost Odyssey remains one of my all-time favourite JRPG, and was one of the main reasons I bought an XBox 360 back then. Other notable reasons were Fable 2 and Mass Effect.