That may sound like a tough one, but actually, the AbleGamers Foundation has an answer, and that answer is Forza 3.
The Foundation, which exists to promote awareness and accessibility in video games for disabled gamers, selects once a year a recipient for its "Accessible Mainstream Game of the Year".
This is awarded to the regular game - as in, one not specifically designed for the disabled market - that is able to best accommodate the needs of gamers with various categories of disability.
Driving game Forza 3 was selected thanks to its wealth of customisable options that allow gamers with a variety of disabilities and/or ailments to still get the most of the game.
Chief amongst these are an "auto-braking" option, which means the game can be played with just two buttons, as outlined in the accompanying video.
This not only aids gamers unable to use their fingers/hands fully, but also colourblind users, as the game's on-track guide to braking - which is red/green, making it useless to the colourblind - isn't needed with auto-braking engaged.
Forza 3's "rewind" feature, which lets users shift the race back to a point in time before a crash or pivotal moment, was also praised, as for those with cognitive difficulties like "those who have trouble making fast decisions on which way to steer", it lets them continue a race after a hiccup rather than restarting.
While none of those options were specifically included in Forza 3 to accomodate the disabled, that's not the point. The point, as AbleGamers points out, is:
What makes this title stand out from the rest is the amount of options given for those who need it. As we always say at AbleGamers, options are the key to including accessibility for those who need it while preserving the difficulty factor for those who don't. Forza 3 gives disabled gamers the tools to tailor the game to their particular disability but does so in a way that if you don't need the accessibility you might never know it's there.
2010 Accessible Mainstream Game of the Year [AbleGamers, via GamePolitics]