Here are some cheats and tips for the game Luigi’s Mansion.
In-game reset:
Hold B + X press Start for about two seconds during game play.
Hidden mansion:
Successfully complete the game and save. Go to the lab.
Professor E. Gadds will ask where you want to go. Select the
hidden mansion to play the game again with various differences..
You can get a different sized house at the end of the game,
depending on your rank.
Gallery mode:
Successfully complete the game to unlock everything in the gallery.