The player is standing on one of the area's platforms when a Boo appears behind them. It attempts to sneak up on the player, but they turn around and stop it. The character then leads the Boo to a nearby portrait, where it is trapped inside the nearby painting, which switches to a red Boo portrait.
The player must lure the Boos that appear toward the paintings that match their colors to earn points while avoiding them.
There are three different colors of Boos: red, blue, and white. Like in standard Mario games, if the player looks at a Boo, it stops moving. The player earns one hundred points for every Boo that is trapped inside a portrait, and one hundred extra points for every Boo that is captured at the same time. More Boos appear every time the previous group is trapped. The game ends when the player is hit by a Boo. In Shroom City mode the player must earn 1000 points to win.
The center portrait, the one the first Boo went through at the beginning, changes every time a Boo goes through it in the order: white-red-blue.
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