Madworld. With the Angry Sun chasing you in EVERY level and every other enemy is in a rage-mode similar to those enemies from Super Princess Peach, with the boss at the end being King Goomba, as he's always ANGRY.
Story: King Goomba is at it again, kick his ass for the 50th damn time.
Solarworld. Where every damn thing is as hot as the fuckin' sun. Get anywhere NEAR THE SURFACE and you'll lose a life due to the extreme heat. Based off of the Star Fox 64 level Solar. Boss is Tatanga.
Story: Tatanga wants the special energy from the sun itself to build his army, and it's up to mario to stop him. You know the drill.
Happy/Sad world. A world with mixed emotions. Boss is Petey Piranha.
Story: Petey is causing a ruckus ruining everyone's day. Make it all come back to him!
Scentworld. A world with odd clouds that have strange effects that will affect the gameplay. Boss is Wart.
Story: A strange scent is being emitted from the mountains causing everyone within the vicinity to act all sorts of weird! Left is Right, Cats chase Dogs and Koopas and Toads are getting along! A strange mystery is afoot, careful of those weird clouds that may be the cause of all this madness!
Boss Rush World (tentative title). Special world that is similar to a boss attack that's known in the Kirby series. All bosses are the Koopa Kids.
Story: The Koopa Kids are fed up with each of their defeat. They challenge Mario for a 7-on-1 duel for a reward stolen from Rosalina, which is now held for ransom. In return.. Princess Peach! Mario will not stand for this!