Mass Effect, Gears of War, GTAIV DLC, BioShock was originally exclusive to the 360. Microsoft picks and chooses what it goes after, but if they want something they'll pay to get it. They gave Rockstar a $50 million loan for the GTAIV DLC, for instance. Things like that have made the 360 versions of multiplatform games the best-selling ones.
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the dreamer of improbable dreams