Bowser's Galaxy Reactor is a Bowser galaxy in Super Mario Galaxy. It is located in the center of the Universe, and is where the final Grand Star is located. Bowser created this Galaxy so he can rule the universe. This level is where the final showdown takes place where Mario and Bowser fight for the fate of the universe.
The Center of the Universe
The path Mario has to take to reach the battle with Bowser is not an easy one. He starts on a small, rocky area resembling part of a castle wall. Using gravity spotlights, Mario makes his way up the walls and arrives at a tower guarded by Dry Bones. At the top a large Gravity Spotlight sends Mario across to the Lava Planet. He must cross this by utilising cooled lava sections moving in the opposite direction to him, and sinking platforms. A second large spotlight carries Mario to the Ice Planet at the end of the pathway. The surface of the ice planet and the lava planet both cause one point of damage if touched. The ice planet's pathway is formed by ice blocks that shoot in from space, but these vanish after a few seconds. The third planet, reached by another spotlight, is made of quicksand, which is fatal if touched. The planet is traversed by narrow platforms which move across the planet against Mario and dip beneath the planets surface. There are also Fireballs in the way. Yet another spotlight takes Mario into a space junkyard where platforms shoot in to form a path and shortly vanish, like on the ice planet. However, gravity arrows and Firebars provide tough-to-navigate obstacles. At the end of the pathway, a gravity spotlight allows access to the Castle Tower, a hollow, cylindrical planet made entirely of lava, stone and metal. Bullet Bills, sinking and moving platforms, Thwomps and Banzai Bills all create a treacherous terrain for Mario. At the end, a launch star takes Mario to Bowser's Final Stand.
Bowser Jr. appears on his airship at the bottom of the staircase leading to where Bowser stands with Princess Peach on board. Junior taunts Mario, then flies behind the platform his father is standing on and begins shooting down the staircase with meteors. Along the way there is a 1-up Mushroom and a Life Mushroom, but grabbing them takes up valuable time. Bowser explains his plan, and then the gravity of a nearby metallic planetoid attracts him and Mario.
Bowser is fought in three phases.
He transforms into a boulder with his head sticking out of the top. If his head is hit by a spiky bush or Mario's Star Spin attack, the Koopa King will fall out of the boulder, and must be hit again to take damage. After he is hurt twice, he and Mario will fly to another planetoid.
Here, Bowser transforms into a ball made of two of his shells. After transforming, the Koopa King then rolls around the planet. Mario must Star Spin into sling plants to knock Bowser onto his back, and then Star Spin him. After doing this twice, Mario and Bowser will fall towards a giant Sun, one of the biggest in the game. It is however, hollow, with holes, and the two combatants will fall through one of these to land on the reactor at the center.
Here, Mario fights Bowser in a similar way to how he does in Bowser's Star Reactor and Bowser's Dark Matter Plant: on a reactor planetoid that resembles a Mario Strikers Charged ball; except Bowser has the attack he used on the second planetoid, which Mario can only avoid. After hitting Bowser twice, Bowser will fall out of the reactor's gravity field and into the Sun. A Grand Star will then be revealed from inside the reactor, which the player takes. As Mario flies away with the Grand Star, Bowser Jr.'s airship plummets towards the Sun, but Mario rescues Princess Peach and flies her to the area where he first entered the Galaxy. It is then revealed that Bowser has survived his fall into the gigantic Sun, but is stranded on the second planetoid upon which Mario and Bowser fought, on a rocky platform which is sinking into the planet, and it gets heavier. As its gravity and mass increase, the planet sucks in more and more rocks from around it, then collapses under its own weight, becoming a giant Black Hole. It begins to suck up everything around it including Mario, Peach, Bowser's Airship Fleet, Peach's Castle, and the Comet Observatory. It would appear that everything is lost until Mario's (or Luigi's) Luma pops out, waves his arm and zooms toward the black hole. The other Lumas join him. The Lumas twist the Black Hole into oblivion, and this results in the resurrection of the Universe and the safe landing of Mario, Peach, and Bowser in the Mushroom Kingdom.
This planet is a planet about 100 metres long. It resembles a crumbling castle and is infested with Gravity Spotlights. These spotlights can be useful due to having their own Gravity. Mario starts on a relatively low platform when he enters the galaxy.
These planets have their own Gravity.
This is a small planet of lava. Mario must navigate his way through this area by using a cooled lava wheel that goes against him. After making his way to the next Gravity Spotlight, Mario will head to the Ice Planet.
This small planet is made of ice, but it is super-cold. Mario will get hurt as if he touched Lava if he tries to swim in the planet's "water".
This planet is a small desert planet. It has a sea of Quicksand. If he falls in, Mario will instantly die. Mario cannot use the Tornadoes to make his way across, as due to their thrust, these tornadoes will only lead Mario to his death.
Space Junk Planet
In order to reach the end, Mario has to cross this small planet. It slowly assembles a pathway that he can walk on. However, it will crumble after a while.
Mario has to use this towering planet's walls to make his way to the top. The walls are covered with Lava, but their extensions can be used as platforms. This area can be considered an area with outward Gravity. It also contains a Black Hole at the base to kill Mario.
Bowser Battle Planets
Bowser's Galaxy Reactor
This is the true Galaxy Reactor. Poised directly at the centre of the Koopa King's sun, it resembles a Soccer Ball from Mario Strikers Charged. Unlike the case with the other Bowser Galaxies, Mario is not thrown off this planet after Bowser meets his fate. Rather, Mario remains on the reactor and he can walk around the planet as of his own volition or grab the Grand Power Star so he can finish the level.
- Bowser's Galaxy Reactor's theme is similar to Rainbow Road from Super Mario Kart.
- This is the only galaxy with standard Gravity on a planet that is not the reactor itself.
- It is also the only boss Galaxy to have their own theme. Bowser Jr.'s Airship Armada doesn't count, since it shares its theme with various places with the Airship theme.