It's hard to choose a Game of the Year when comparing video games from different genres but with my main criterion being ambition, there's no need to look for game of the year further than Fallout: New Vegas, the combination between action and role-playing game created by the team at Obsidian and published by Bethesda, who are now the holders of the franchise.
The great triumph for New Vegas is that it delivers a world which is closer to feeling alive than any other delivered in video gaming this year, including that of Mass Effect or that of Fable III.
The post apocalypse is believable and oddly beautiful and all the factions involved in the various stories and quests have motivations that are consistent and make sense within the confines of the world.
Obsidian sure knew video game writing and Fallout: New Vegas is the perfect showcase, allowing them to execute a number of callbacks to the previous titles in the series while also creating new gags and situations.
Everyone who plays should take the time to go to Vault 11 and read the scraps of information which deliver the chilling narrative and Caesar, with his mix of charisma and absurd moral code, is one of the most interesting characters I met in 2010.
Obsidian has also made New Vegas tougher than Fallout 3 and more rewarding, with feats like taking out the Alpha Deathclaws really being something to brag about around the office, adding gravitas to the world.
Yes, the game had a lot of bugs initially, linked to technical problems, like inexplicable crashes to desktop and freezes on consoles, but also to how the game progresses, leading to quests that cannot be completed and weird world results.
Obsidian has pushed out a number of patches which improve things significantly and it seems that the game could get a stream of downloadable content as long as Fallout 3.
Fallout: New Vegas has longevity (one playthrough can go to 60 hours easily), has replayability (at least four main paths and many more possible variations) and has character and that makes it my 2010 Game of the Year.