THE DEMO IS HERE! GET EXCITED!
Demo:
https://bin.smwcentral.net/u/47437/Mario%2527s%2BGrand%2BAdventure%2BDemo.bps
Fair Warning, this demo is from an earlier stage in development than these screenshots, so there may be some minor or major differences from the Final Product.
Welcome to the Fungus Islands! Bowser has given up trying to kidnap Princess Peach (for now), and his son, Bowser Jr, has set his sights on the Fungus Islands. Mario, being on vacation there, naturally, has to stop Bowser Jr's plans, along with Luigi. Can the brothers stop the Colonization of the Islands?

The Title Screen

World 1's Map

World 2's Map

World 3's Map

World 4's Map

World 1-1: A Basic Grassland, complete with slopes!

World 1-C: The first Castle...(sniff)...smells like Layer 3!

Iggy Koopa: Huh. No Layer 3 here. Ah well, still a neat boss!

World 2-2: An Ancient Temple, with...a statue of Donkey Kong?!

World 3-2: A Frosty Cave, with pointy crystals.

World 4-3: An Abandoned Testing Facility, Watch out for that toxic goop!
I haven't made a screenshot for World 5's map yet, but I'll tell you that it's beach themed, nor have I made a screenshot for World 6's map, which is volcano themed..
Thanks for checking out what I have so far!
- Apple Boy