Mario winds up on an island of Bowser's where he must compete against Bowser's 18 (not 19) new courses.
The game is cleared when you beat Bowser, and to do so, you play all the other levels until you find 4 different switches to form the bridge to Bowser's castle, similar to EVW (plot is still the same).
-IMPORTANT: If a level is too difficult, leave it unless you are trying to get 100% (every Dragon coin in every level, every 1-UP secret and every 3-Up Moon).
-Two-toning and new tiles (a spiky star in a castle works like a normal spike)
-Toxic water (you could only survive for 30 seconds)
-Evacuation (blowing up a reactor core then getting the hell out)
-Difficulty levels (explained in Introduction #2)
-3-Up Moons hidden in every level with a medium difficulty or higher.
-Variety of ways to finish the game.
-Further reduce of unfair situations, stale bullet jumps, flaws, glitches, and complete fix of failure to load sprites
-Important fixes such as taking out the ability to leave the boss battle because of side exit, fixing bad palettes, making Diver Down possible to beat once again and a noticeable decrease in cutoff, both in levels and on the overworld.