Matter Splatter Mansion

Matter Splatter Mansion is the sixth and secret level of Ghostly Galaxy from Super Mario Galaxy. This mission's concept is very similar to the Matter Splatter Galaxy, where matter forms and destroys platforms, requiring Mario to act in accordance to where the matter creates platforms to proceed through the level. It can be accessed by playing the level A Very Spooky Sprint.

Layout
At the mansion's gate are two stalagmites, one of which is glowing. Breaking the glowing stalagmite will reveal a Launch Star that will send Mario to the Darkness Room Planet. Stepping onto the circular light will cause it to move forward and reveal the path, which the player has to keep up with, followed by collecting the key at the end to open the door. Stepping onto the next light will cause it to move backwards, revealing stairs and gaps as it moves along. The next room has a key, which will unlock the two doors it is in front of. Touching the ? Coin found behind one of them will start moving the spotlight upward, and the player has to make use of Wall Jumps to progress. At the top of the area are four doors that will be unlocked by touching a nearby key; behind one of which is the Power Star.

Trivia

 * The mechanics of this mission, as well as Dark Hopper Planet C and Dark Hopper Planet D in Matter Splatter Galaxy, are similar to the autoscroll levels seen in many platformer Super Mario games.
 * The Hidden Halls Planet from Haunty Halls Galaxy is similar to Darkness Room Planet in concept, but instead of following the light like an autoscroll level, the player has to use Bulb Yoshi to reveal the path.