This game is a very well done and thorough hack of Super Mario World,
adding an entire new set of levels, a new world map, and even ASM-coded
several other interesting features into the game's engine, such as a
blue block that can be broken only by firepower. The layout of the
game takes full advantage of both the mechanics of Super Mario World
and the additions of Super Demo World, and the levels can get extremely
complicated.
The homepage for Super Demo World, including the patch to be used on a Super Mario World ROM, and the program used to make the hack, is available online.