The Boss Demo is the demo that shows the completely finished 7 Koopalings' Fusion Boss. It's very similar to the 7hero Demo, the only differences are: the 7 Koopalings' Boss is complete and there is an extra level in the Bowser's World that leads to Bowser's optional second phase (removed in the next version).

It's the prequel to the demoOnly1 and the sequel to the 7hero Demo.