Legend:
Difficulty: How hard a level is: Easy, Moderate, Hard, or Brutal
Midway Point: If the level has a midway point: None, Gate, or Hidden
Boss: If the level has a boss: None, Mini-boss,or World Boss
Exit: What kid of exits: Normal, Secret, Second, Shadow Comet(Daredevil, Speedrun, Race), and/or Purple Comet
Difficulty: How hard a level is: Easy, Moderate, Hard, or Brutal
Midway Point: If the level has a midway point: None, Gate, or Hidden
Boss: If the level has a boss: None, Mini-boss,or World Boss
Exit: What kid of exits: Normal, Secret, Second, Shadow Comet(Daredevil, Speedrun, Race), and/or Purple Comet
WARNING: Spoilers Ahead
World 7 - Blooper Zone (100% Complete)
In World 6, not to far from Bowser's Castle is a warp pipe taking you to World 7, the Blooper Zone. The golden star there could be in any level.
World S- Special Zone (100% Complete)
Like SMG2, 2011 has a new world. You will need Luigi to complete this hidden world. At the end is the ultimate challenge that very few can beat.
World D- Developer Subspace
A whole new world for the creator(s) of the game and where all stuff is tested. For designers and programmers.