The Fiery Stronghold

The Fiery Stronghold is the only mission of Bowser's Star Reactor in Super Mario Galaxy. The mission's objective is to defeat Bowser.

Layout
The player begins in a Warp Pipe-like structure with a couple of Fire Bars and a Luma. Moving along the multicolored path, the player will reach a stone structure with Fire Bars, a Fire Cannon, and a Thwomp. Behind the Thwomp is a side-scrolling area where gravity is determined by where arrow directions. By avoiding the Fire Bars, Black Holes, and a Thwomp, the player will reach a circular platform with Fire Bars in an "X" formation. The path ahead will wind around a stone tower and has many Thwomps, Fire Bars, and Fire Cannons. When the player reached a certain point on the tiled platforms, Bowser will appear and begin firing meteors, attempting the break apart the platforms as the player climbs up. Additionally, on one of these platforms is a Life Mushroom. Once the player reaches the top of the tower, Bowser will begin a dialogue, and the boss battle will start soon after.

At the end of the dialogue, Bowser will send him and Mario to a small planetoid above. Bowser will attack by jumping into the air and landing where Mario is standing, causing shockwaves to form upon landing. If the player can get Bowser to land on one of the blue areas, it will shatter and Bowser will burn his tail on the lava underneath, which will cause Bowser to start running around the planet. By catching up with him, Bowser will turn around and the player has to spin into his tail, which will flip Bowser over. Spinning into him once more will damage him and start the next phase. The second phase starts with Bowser shooting fireballs, followed by jumping and sending out two shockwaves. He will then attempt to jump on Mario once more. After spinning and flipping him over, this time Bowser will start moving across the planet. Spinning into him once more will start the final phase. The third and final phase begins with Bowser shooting out more fireballs and shockwaves than last time. Afterward, he will attempt to land on Mario again, though he will now be running and spinning faster than the previous phases. Additionally, the player has to spin into Bowser twice when he's flipped over. After defeating Bowser, he and Mario will fall back down to the tower and Bowser will disappear, leaving behind the Grand Star.

Enemies

 * Goombas
 * Fire Bars
 * Fire Cannons
 * Thwomps
 * Bowser (Boss)

Planets visited

 * Starting Planet
 * Gravity Planet
 * Stairway
 * Star Reactor