There is a cancelled sequel for Super Mario 64, commonly called "Super Mario 64 2" or "Super Mario 128" (not to be confused with the tech demo of the same name) for the failed N64 DD. Only one demo was ever made, but was never shown to the public. The only information known about the game is that Luigi was going to feature in it, and co-operative play was a speculated feature. Since these two elements feature in Super Mario 64 DS, it's possible that other elements from Super Mario 64 2 were incorporated into Super Mario 64 DS.