Bowser's Galaxy Reactor


 * Not to be confused with Bowser's Galaxy Generator.

Bowser's Galaxy Reactor is the final galaxy in Super Mario Galaxy (not counting the Grand Finale Galaxy). It is located in the center of the universe, and can only be accessed by talking to Rosalina onboard the Comet Observatory, which she will then transform into a comet and fly to the center of the universe. This is where the final Grand Star of the game is located, and as such features the final battle between Mario and Bowser. Bowser Jr. watches from the sidelines on his airship while holding Princess Peach captive. After the final battle, Bowser's large sun implodes and reforms into a huge Black Hole, causing the entire galaxy to collapse in upon itself, after which it begins to suck up the entire universe, along with Peach's Castle and the Comet Observatory as well. The Lumas all throw themselves into the Black Hole to reverse its effects and prevent the destruction of the universe, after which the universe is reborn, and Mario, Peach, Bowser, and many others land safely back in the Mushroom Kingdom.

This is the first area that Mario encounters after entering the Warp Field inside Peach's Castle. The extensive vertical walls of this strange area appear to be part of a crumbling castle. This particular section of the level contains special Gravity Spotlights which allow Mario to walk directly up the vertical walls when the gravity field of the spotlights is entered. Several Dry Bones also patrol the area, and can trip the player up if they are not careful.

This planet is the first of three element planets that are encountered one after another. The planet itself is made completely of lava, though it does have multiple steel platforms rising out of the lava, along with moving sections of cooled lava which form moving pathways across the diameter of the planet. The steel platforms on the planet will begin to sink down into the lava as soon as Mario sets foot on them. The only significant obstacles that Mario will face on this planet (aside from the sinking platforms) are Podoboos and steam geysers. A few coins can be found on certain parts of the planet, along with a 1-Up Mushroom.

This planet is similar and seemingly larger than the lava planet and is the second element planet, but is made out of ice instead of lava. It has ice blocks that create a path across its frozen surface. The ice blocks last for about 6 seconds before they disappear, meaning that they must be navigated quickly. Interestingly, the ice surface of the planet acts like lava (it could possibly be a form of dry ice).

This planet also appears to be larger than the previous planet and is the last element planet, but is made of sand. To get across this planet, Mario must follow moving stone paths to avoid Firebars and instant death quicksand. In this sense, it is rather similar to the Lava Planet, as both planets involve a narrow, moving pathway with a deadly substance making up the remainder of the surface and fire-based obstacles. A pair of Galactic Tornadoes can also be found here, although they are of no use to Mario, for they only lead to his doom.

These are blocks that float around space, but when Mario gets close to them, the glowing blocks begin to appear beneath the plumber's feet, which forms a path for Mario to continue. If Mario stays on the platform too long, it will disappear. Mario must also deal with alterations in gravity's direction, and time his movements to avoid Firebars.

This planet is a cylinder resembling a castle tower, though the inside is walled with lava. This planet has Bullet Bills, Banzai Bills, and Thwomps. Mario must travel to the end to reach the Launch Star using moving and sinking platforms while avoiding all enemies and obstacles with limited cover and a sparse supply of coins.

This is the pathway toward the battle between Mario and Bowser. It consists of a flight of stairs. There are two side platforms that contain a Life Mushroom and a 1-Up Mushroom. But if Mario wishes to get these, he must do it quickly because the path will crumble when Bowser Jr. shoots meteors from his airship.

This first planet is where the first stage of the final battle takes place. It has spiky plants growing on the surface. Mario can have Bowser crush the plants to get Star Bits and coins.

This second planet is where the second stage of the final battle takes place. It has Spiky Plants and Stretch Plants growing on the surface of it. Mario can have Bowser crush the plants or spin the trees into the plants to get star bits and coins.

This last planet is where the third and final stage of the final battle takes place. It only has coin lamps on the surface, which Mario could shoot Star Bits at to get coins. The reactor is surrounded by a sphere of lava that makes up the massive sun of Bowser's galaxy.

These are two more unreachable planets off to the side of the element planets. One is completely made of water and the other of Lava. The only way to reach them is by hacking the game.

Enemies

 * Dry Bones
 * Firebars
 * Podoboos
 * Galactic Tornadoes
 * Bullet Bills
 * Banzai Bills
 * Thwomps
 * Bowser (boss)

The Fate 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 climbs 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 Firebars 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. He taunts Mario, then flies behind his father and begins shooting down the staircase with meteors. Along the way there are a 1-Up Mushroom and a Life Shroom, but grabbing them takes up valuable time. After Bowser explains his plan, the gravity of a nearby metallic planetoid attracts him and Mario. 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 spin attack, he will fall out of the boulder, and must be hit again to take damage. After he is hurt twice, Mario and Bowser will fly to another planetoid. Here, Bowser transforms into a ball made of two of his shells. He 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 centre.

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 he fought with Mario, on a rocky platform which is sinking into the planet. 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 its arm and zooms toward the black hole. It is soon joined by all of the other Lumas. The Lumas twist the Black Hole into oblivion, but appear to be destroyed in the process.

Trivia

 * On the planetoid made of sand the player can reach the Galactic Tornadoes by long jumping off the moving platform and Star Spinning at the ending height of Mario's long jump. The Galactic Tornadoes do nothing good for the player and they occasionally launch the player into space, making Mario lose a life.
 * An upside-down "L" made out of Star Bits appears on the wall of one of the platforms.
 * On the lava planet if Mario (or Luigi) stands on the edge of the solid rock platform just before the next gravity spotlight beam and go into first person view and looks at the right, the player will be able to see the castle tower where Bowser is standing. Also, if the player slowly moves Mario's (or Luigi's) sight around while looking at the castle tower the player can see a misplaced gravity spotlight beam on the star under the castle tower.
 * In the first battle with Bowser, he uses an attack where he encases himself in a boulder, similar to the new Rock Mario ability in the sequel. It is possible that this attack along with the behavior of Boulders was the inspiration for this power-up.
 * When Mario is pulled to the Brown Planet (this is the second planet encountered in the final battle), normally, the player is supposed to wait until Bowser is done launching fireballs from his mouth, and then use the multiple Stretch Plants scattered around the planet to hit Bowser when he curls into a spiky ball and rolls around the planet, thereby causing him to fly helplessly around the planet on his back, and leaving him vulnerable to futher attack. However, if the player does not wish to wait for Bowser to finish his fireball attack, they can simply approach Bowser before he rolls into a spiky ball and spin the Stretch Plant nearest him, which will also cause him to fly around the planet on his back, thereby eliminating the need for the player to endure both of his attacks, and creating a shortcut.