In an unusual twist, this plays from the perspective of a villain in the Mario series. As such, Boo NPCs are friendly to you. Some ghosts aren't, and for those, you just have to pay attention. Other Mario enemies are predictably still enemies to you.
While the second level and the castle level were lazy, the other two were decently designed and had a cool concept thanks to some custom blocks and sprites. This hack also has a boss at the end of every level.
The difficulty curve in this hack is non-existent. The rain level and the last boss in the demo stick out like sore thumbs, being considerably harder than the rest of the levels.
Two notable problems, one of which hurts the rain level, are sprite tile memory issues causing a platform not to spawn (although if you scroll the screen with the R-button and run, the jump is still doable) and the message from the last boss of the world being blank.
The overworld's a little messy: while the layout's there, nicely decorated although blocky, there are no paths leading from level to level.
I feel ambivalent about this hack... it's mostly enjoyable and has the potential to be awesome but has a fair number of missteps and I'd hope to see them addressed should the author still be working on it.