Goal Door (Mario vs. Donkey Kong series)

Goal Doors, also known as M Doors, Exit Doors (also uncapitalized as exit doors),  or generically the exit,  the goal, or the door, are the main objective in most non-boss levels in the Mario vs. Donkey Kong series. Minis must enter these doors to complete the level.

Mario vs. Donkey Kong 2: March of the Minis
Goal Doors debut in Mario vs. Donkey Kong 2: March of the Minis, where they are generically referred to as the exit and appear as curved, yellow-colored jambs with an "M" symbol imprinted on them. In this game, the objective of each level is to guide at least one Mini into the exit. When a Mini enters the exit, it sparkles. If multiple Minis consecutively enter the exit while it is still sparkling, a Chain Goal bonus is activated, adding to the level's score. The level will only end when all Minis in the level have either reached the exit or have been destroyed; however, if every Mini in the level is destroyed, the game is over.

The exit also appears in Mario vs. Donkey Kong 2: Cannon Kaos, serving as the exit of the final level, Level 3. The player is awarded 10 coins for every Mini Mario that reaches the exit.

Mario vs. Donkey Kong: Minis March Again!
Goal Doors return in Mario vs. Donkey Kong: Minis March Again!, where they are referred to as both the door and the exit. However, they function differently from the previous game. When a Mini enters the Goal Door, a timer appears above the door and begins counting down. If this timer runs out before all the Minis in the level reach the Goal Door, the door is boarded shut and the game is over. The timer resets if another Mini reaches the Goal Door. Additionally, every Mini must reach the Goal Door to complete the level; if a single Mini is destroyed, the game is over.

In this game, the "M" symbol on the door's jamb is absent, and the jamb has a thin inside border of a hot pink color. While Minis are entering the door, it sparkles and the jamb's inside border turns blue. When all Minis in the level have entered the door, the jamb's inside border reverts to hot pink, and the door closes.

Mario vs. Donkey Kong: Minis March Again! introduces locked doors, which must be unlocked by a Key Mini Mario before any Minis can enter it.

Mario vs. Donkey Kong: Mini-Land Mayhem!
Goal Doors appear in Mario vs. Donkey Kong: Mini-Land Mayhem!, where they are known as Exit Doors. They function identically to their appearance in Mario vs. Donkey Kong: Minis March Again!. In levels with only a single Exit Door, the door has a golden border and a red frame with Mario's "M" emblem, and the timer is displayed inside of the Exit Door, rather than above it. Locked Exit Doors also appear in this game, which must be unlocked by a Key Mini Mario like in the previous game.

Mario vs. Donkey Kong: Mini-Land Mayhem! also features Multi-Door levels, where each Exit Door is assigned to only one of the playable characters — Mini Mario, Mini Toad, Mini Peach, Mini Donkey Kong, or Mini Pauline. They are colored red, blue, pink, yellow, or sea-green, in respect to each character. Each Mini must be brought to its respective Exit Door. Exit Doors assigned to characters do not have a timer.

Mario vs. Donkey Kong: Tipping Stars
Both regular and assigned Goal Doors reappear with the same functions in Mario vs. Donkey Kong: Tipping Stars, along with a green Goal Door assigned to Mini Luigi. In this game, the criterion that all Minis in a level must reach the Goal Door consecutively to one another is known as the Chain Rule.

Mini Mario & Friends: amiibo Challenge
Goal Doors reappear in Mini Mario & Friends: amiibo Challenge. In this game, the "M" symbol on the front of the door is replaced with a red flag. Variants of Goal Doors known as amiibo Doors also appear.