Even though there are other games on the system that sold more, I would argue that Wind Waker is the game that defined the Gamecube more than any other – and mostly to the Gamecube‘s detriment, imo. I mentioned this before, but I think the reveal of Wind Waker with its ultra cartoony artstyle is what doomed the Gamecube to its status as the kiddie console, and let to it being left behind in third place in that generation. The early 2000s were the worst possible time for Nintendo to do a ‚kiddie‘ Zelda; at that time everything and everyone tried to be ‚dark‘, ‚edgy‘ and ‚mature‘. Especially
after Nintendo had already shown with their Spaceworld 2000 tech demo what a next-gen Zelda game with OoT-style graphics could look like:
I genuinely believe that if Wind Waker had looked more like that tech demo, the Gamecube would‘ve been perceived very differently, and would’ve sold quite a bit more early on. This early momentum could’ve carried them through the rest of that generation, and the Gamecube would’ve probably outsold the XBox by a comfortable margin.