Bowser's Fortified Fortress

Bowser's Fortified Fortress is the first mission of Bowser's Galaxy Generator in Super Mario Galaxy 2 and also the final story mission in the main game. The objective is to defeat Bowser for the final time.

Mission
Mario starts off on the Starting Planet, and from there progresses to the Platform Planet. There, Mario must defeat three Hammer Bros in order to make the Floaty Fluff appear. Mario can use this to glide past multiple fireball cannons on the Volcanic planet and fall onto a small circular area of dirt; however, he can save time hugely by touching a wall of lava and using this momentum to fall to the bottom safely. Here, Mario must use the Spin Drill to burrow through the ground to the Banzai Bill Planet. Still retaining the Spin Drill, he must gradually work his way around this planet, being careful to avoid the numerous Banzai Bills that fly around it. He must locate one specific square patch of dirt amidst all the others and burrow through it, revealing the Launch Star to the Castle Tower Planet.

Here, Mario must work his way through the planet, dodging multiple Bullet Bills that attempt to block his way. When he reaches the end of the planet, another Launch Star will lead him to the Bridge Planet. Mario will have to release Yoshi from his egg, and use his tongue to grab onto the flowers to swing onto the Magma Planet. After defeating two more Boomerang Bros., a large section of the wall will open up on the planet, revealing a Dash Pepper which Yoshi must use to speed through the wall section of the planet before it closes on him. After avoiding some Magmaarghs on the next section of the planet, Snake Blocks will lead Mario and Yoshi to the Big Door Planet, where Mario must Ground Pound meteorites into three stone locks to unlock the door, leading the way into the third and final Bowser Battle of the game.

After unlocking the big door, a gravity field will pull Mario in, who, after being threatened by Bowser, will be taken to the Bowser Battle Planet, where he must again battle Bowser for the final time. He must Ground Pound meteorites into him four times to release the Grand Star, but just as Mario approaches the the Grand Star, Bowser, who has somehow gotten huge again crashes through the planet's floor and eats the Grand Star, causing him to become even bigger. In this second phase, Mario will be pulled to meteorites, he must Ground-Pound his meteorite platforms into Giant Bowser four more times, causing Bowser to fall into the massive black hole in the background. Should he run out, a new meteorite will spawn. The symbol on the meteorite can help Mario aim his shot; it always faces directly away from Bowser, so ground-pounding in the direct center of the symbol is a sure shot.

After the battle, Mario will be taken to the Garden Planet, where he is reunited with Peach, and is able to collect the sixth and final Grand Star of the game. This enables the player to view the first ending sequence, the ending credits, World S, and the secret ending, if 120 Power Stars are collected.