How would you change a game?

[BullockDS]

To start things up, it would be really cool if they added a few more courses in Super Mario 64. Since Nintendo was going to implement over 30 worlds into it during development, it wouldn't hurt to squeeze a few more in. All they need to do is move some of the castle secret stars into the star set for each world and remove the somewhat tedious 100 coin missions. That way, they would have plenty of stars to use for a few more levels.

Oh hell yes. I'm just gonna go ahead and tack on some more shit to the SM64 list:
-better, more flexible camera, a la Sunshine's (in fact, there's an ASM hack for this already, and my god is it glorious)
-add Luigi, but make him not as game-breaking as he was in SM64DS, give him the ability to walljump, and let him fight Final Bowser (I'd probably make Luigi unlockable by some random-as-hell, obscure means as a callback to the countless and absurd "OMFG PALY AS LUIGI IN SM64" rumors)
-more specifically for some extra levels, I'd totally throw in an extra basement or tower floor of harder levels only accessible after beating the game once, and then a super-duper tough level accessible after gathering all the Stars in the game (much like the past few 3D Mario titles)
-Co-op mode (again, there already does exist a Mario+Luigi hack for this)