Megaleg's Moon

Megaleg's Moon is the first boss mission of Super Mario Galaxy. It is found in Bowser Jr.'s Robot Reactor. The primary goal in this mission is for Mario (or Luigi) to battle Megaleg.

Layout
Mario initially lands on the Starting Planet. There are three cages on the planet that must be hit by Bullet Bills and a couple of Goombeetles. Mario must get a Bullet Bill to a cage that contains a Launch Star leading to the Robot Reactor, where Megaleg is fought. Mario starts on the ground and Megaleg blasts Bullet Bills and tries to step on him to defeat him. There are multiple cages on the other side of the planet that a Bullet Bill can break open. If Mario runs up Megaleg's leg when it is on the ground, he reaches an area where three Bullet Bills are blasted at once. After dodging those Bullet Bills he must then move on to a turning gear area where he must hop the gears. Finally, he reaches Megaleg's head where there is a cage and a Bullet Bill launcher. Mario must destroy the cage to open up another cage, this one being regenerative, that he must destroy and a third cage in the middle of that one. Once Mario destroys all the cages, Megaleg explodes and Mario falls to the ground with the Grand Star.