By the time Halo 3 came out the MP FPS lobby shooter genre was already well established thanks to it's predecessor. H3, as good a game as it was/is, did not have the same impact on console gaming that Halo 2 or CE did. The mid - late 00's were absolutely dripping with MP shooters with the likes of CoD and Battlefield on the rise. It was still a standout game of 2007 but more important than Bioshock? Not really.