Really great hack, I enjoyed it its definitely something new to try, I enjoyed it until a level progression bug happened right before World Elek-Tron, where The boss of World 2 is unbeatable due to the game crashing on SNES9X.
Surprisingly the game runs well also on a emulator on a console (I used my Wii)but the BG Exgfx bugs are definetly happening way more on there than on a emulator on pc.
The Level design is great, felt pretty straight forward, although I found myself going back to get something I forgot, it was nice and simple.
The Music Selection is Great, every song fits its theme, I also like how the SMB2 Overworld somehow suits the city levels.
The Graphics are Amazing, really well done, I assume the buildings are custom, they are really detailed and well made, I like it, and the pallet selection was alright also, props to you for that, if it wasn't for that GFX bug on SNES9x it would of been perfect.
Difficulty, was fine, It had a good flow of easy at the beginning and then like usual world 2 gets harder and so-on.
I give it 4 Stars, its really buggy on SNES9X, and While I do not want to biased about it, ZSNES is a Older Emulator that is really outdated, Testing should be Done with BSNES so that compatibility is assured, good job though, hopefully one day it will be complete.