You can hop in the moat and wonder how to access that submerged door while simultaneously figuring out that Mario needs to come up for air or he'll drown. You can jump over to a lake and wonder what the deal is with that cannon that has a grate over it. You're standing in a garden, facing a pathway that leads toward a castle in the near distance.

When Super Mario 64 finishes laying out the bare-bones plot (Princess Peach baked you a cake, she's been kidnapped by Bowser, etc), and first gives players control over Mario, nothing happens. Instead, it's Princess Peach's Castle itself, an innovative spin on the idea of a 'hub world' that showed players that there were secrets to be found right from the start. Super Mario 64 sent the mustachioed plumber to all sorts of memorable worlds during his quest to snag Power Stars and rescue Princess Peach from Bowser's clutches, but more than two decades later, it's not Bob-omb Battlefield, Lethal Lava Land, or Cool Cool Mountain that you remember most.