It's basically going to be both SMB2 and SMB3 themed, and I'll try to mix these two as much as possible and make it fit. I'll try to make it more interesting with a few personal touches here and there, though. There are going to be two playable characters: Peach and Toad.
Story
I'm still working on it, but it won't be anything overly complicated, and I'll try to keep it similar to most Mario games's plot. I'll try not to go with generic stuff like "Bowser kidnapped a random princess, go save her!", though :P
Progress
I've started it recently and don't have much to show, so here's a screen of level 1. It might look a bit flat from the screen, but it's the start of the level, and considering most Mario games are a bit linear I don't see any problem with it personally.
Screenshot: