6. Mario Tennis: N64, 2000, Nintendo/Camelot
Tennis, a very simple game, but Camelot struck gold. Despite being Mario-themed, this game really had very few gimmicks, aside from the Bowser Court mode which did have items. It was sheer mechanical refinement that made this game infinitely replayable: they made Tennis *fun*, gave the world Waluigi, and linked with the Game Boy Color version so that you could raise your GBC character on the N64. Not really sure what they did right, but damn did they do it right.
Monster Hunter: pissing me off since 2010.