A couple years ago I came up with a hypothetical 2D Mario platformer called New Super Mario World and designed a bunch of concepts for it by slapping together spritesheets and pieces of backgrounds. That's... pretty much the gist of it. My Paint/Photoshop prowess wasn't exactly up to par yet, but it was still kinda neat for what it was and the reveal of Mario Maker reminded me of it so I thought I'd share. It's more about the ideas than the quality of the edits themselves, really. Maybe if you guys like it I'll try my hand at an updated version or something similar and see if I can make it look fancier.
Here's World 1:1-1 The Adventure Begins1-2 Hammer Bro Caverns
(IIRC the green font just means it's an underground stage?)1-3 Rippling River1-4 Hidden Heights1-5 Foothill FortressEnemy Course1-6 Piranha Plains
(5 on the map)1-7 Larry's Villainous Villa
The numbering system is all jacked up since I used numbers for Fortress and Castle levels, but it's not too hard to make sense of I guess. World 2 should be coming sometime soon!