They're all fantastic, though I don't think SMB was actually a launch game right? I gotta go with Mario 64. 3D was still new and it just revolutionized what a 3D game could be like. It was simply incredible. Wii Sports also gets up there as maybe my second vote because it introduced a brand new way to play games in a super fun way, it literally launched tens of millions of Wii sales. The most unexpected blockbuster title of all time.