Just what it says on the tin. I think it'd be awesome to have an option or separate game mode that completely randomizes the levels. On Random Mode you would start off on 1-1, and the last level is still 8-4, but everything else from there is completely randomized. You could potentially go through three palaces in a row, followed by two Lakitu levels. You could still take the warp pipe in 4-2 to 8-1, but now that has the potential to move you backwards. You don't know, it's random! Gaah! I think it'd add a great amount of replay value to the game: it's unpredictable, but still not terribly game-breaking as the play styles and strategies for each level would remain unchanged. And it'd be painfully simple to do, from a programming perspective. Another possible variation could be Short Play: play through a randomly-selected four levels, twelve levels, or however-many levels. We could try for completion, high score, or even time.