The Mushroom Desert is the largest area in Super Mario GameBox Demo. It consists of 5 areas.
Swarmed by Desert Mowz, this area is the second largest. The Boss Key is located under a pillar. The pillar is guarded by a Sand Whomp.
The oasis used to be there, but dried up. A faucet is in a tree. Filling the oasis reveals a Boss Key.
Filled with Gritty Goombas, the place is the tomb of Tutanchomp and is large, being the 3rd largest area. The Boss Key is guarded by Tutanchomp, who must be defeated for the key.
The largest area, along with being the most puzzling. The key is hidden beneath sand. At the bottom is the Boss Door.
The boss of the level is Sand Chomp. After Sand Chomp's defeat, a Power Star piece is collected.