Castle Clearout

Castle Clearout is an extra minigame featured in Mario Party 9. One to two players can play.

In "1 Player" mode, players can earn "2" party points for each level that they clear; in "2 Player" mode, players can earn "5" party points when the game is finished.

Gameplay
In single-player mode, the player can first select which level they may play (however, he or she must choose level one if it is their first time playing), and there are 50 levels total. The game is like Dr. Mario, in that the player must clear levels by placing a group of six marbles onto the ground to clear the marbles with a star pattern on them, as well as similarly colored marbles. The player can achieve this by rotating the marbles to match colors with them.

Clearing a group of marbles with similar colors in the shape of a line, pyramid, or hexagon also clears any other marbles of the same color. As the player passes through levels, more and more marble colors will appear. Colors include red, blue, green, yellow, and purple, with the former three being the default colors.

Another similar element to Dr. Mario is that the player must avoid having the marbles touch the top of the area, or he or she will lose.

Lastly, as the player advances through each level, the marbles will gradually fall at faster speeds, which can make it even harder to place them at the areas that the player wants. Additionally, the amount of marbles to start out with will gradually increase too.

In two-player mode, the players may select whether they want hints or handicaps or not. Both players start with an empty field, though gameplay is the same as the single player version. Additionally, clearing marbles in one of the formations causes marbles to fall onto the opponent's field. Players win when their opponent has stacked marbles above the red line, and the first player to win three out of five games wins the match.

In-game text

 * Description from Extra Mode – "Connect six or more marbles of the same color to clear a group. Clear a group of marbles in certain patterns for special results."
 * Rules 1 – "Connect six or more marbles of the same color to make them disappear. Clear all of the star marbles to move on to the next level. Clear marbles in certain formations for special results."
 * Rules 2 – "These formations include Line, Pyramid, and Hexagon. Clearing marbles in a formation will cause all other marbles of the same color to disappear."
 * Rules 1 (2 Players) – "Connect six or more marbles of the same color to make them disappear. Clear marbles in one of the three formations to send extra marbles raining down on your opponent!"
 * Controls – "Hold the Wii Remote sideways. Press left or right on to move the marbles, and press down to make them drop. Press  to rotate marbles left and  to rotate marbles right."

Trivia

 * If a player gets a Game Over in single-player mode in this minigame and doesn't break the current record, the player's character will do their 4th place animation and say a quote that isn't used elsewhere in the game (for example, Mario saying "Mamma mia!" or Toad saying "Oh, no!", one that is reused from Mario Party 5).
 * The "Too Bad!" message will also appear instead of the level number if the player fails the first level of their session (the "You Won!" music plays regardless, however).
 * This is the only minigame where the "Too Bad!" message plays the "You Won!" music. Other minigames played the "Failed..." music.
 * In the Nintendo Switch game Clubhouse Games: 51 Worldwide Classics, this game reappears under its Japanese title and without Mario elements.