What I think was so important about Majora's Mask was that it divorced games once and for all from cinema and literature. They're basically linear while games are cyclical ... we often play bits again and again (learning a boss's moves, for example), and MM made a whole game out of that premise, repeatedly putting the player through the same hour of gameplay while pushing them forward spatially. It may not have been as involving as OOT, but it was cleverer. Shame it hasn't been more influential. My favourite was Wind Waker, though. Loved the whole anime look ... why was it so unpopular!