Door

A standard red door.

Doors are found in the Subspace Emissary and Smash Run. When interacted with by pressing the up direction of the control stick, they transport the player to another room.

In the Subspace Emissary

Regular doors

The most common doors are red in color with a pointy top, with blue light shining out from the edges. They transport act as checkpoints: if the player runs out of stocks (i.e. game over) and continues, they will respawn next to the door they had last entered. Most doors lead to the next area and are one-way, but some lead to special rooms which often contain cubes.

Some stages feature differently-looking doors, which however do not change in function. In the stages in the Halberd, the doors are bronze in color, and slide open instead of opening from the middle. In the stages which feature the Research Facility and the Subspace Bomb Factory (i.e. the Isle of the Ancients), the doors are gray in color with black stripes. In the Subspace stages, the doors will open like the red ones but are purple and have what appear to be scales on it. Uniquely, two areas in the Subspace Emissary are entered without doors: in The Ruined Zoo the player enters what appears to be the entrance to an abandoned aquarium, and in The Lake Shore they enter a cave through a large opening.

Doors increase the player's clear percentage: to reach 100%, all the doors in all the levels must be entered.

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  A door found inside the Isle of the Ancients.

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  A door found in the Halberd.

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  A door found in Subspace.

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  An opening that functions as a door in The Ruined Zoo.

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  An opening that functions as a door in The Lake Shore.

In The Great Maze, several special-looking doors can be found:

• orange doors with a yellow circle in the middle lead to save points.
• doors with black smoke emerging from the edges indicate that there will be a Subspace Clone/Boss behind them.
• the very last room of the Great Maze contains a large purple door which leads to Tabuu's Residence.

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  A door leading to a save point.

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  A shadow bug door.

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  The final door leading to Tabuu's Residence.

Ending doors

In some stages, the end of the level is illuminated by rays of light. Entering the light will make it brighten until the screen goes back, at which point the regular finish screen appears. If the stage is completed again, the light will be replaced by a golden door.

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  A gold door at the end of a regular stage.

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  A gold door at the end of a stage in Subspace.

Day-changing doors

An orange day-changing door.

In The Lake and the part of the Great Maze based on The Forest there are day-changing doors that are yellow or sky blue with a triangle in the middle. Entering one of these doors lead the player to an area very similar to the one they just left, but with some key differences, like the overall color scheme, the enemies present and what blocks are breakable. The actions of the player in one version of the world also affect the other: for example, it is often necessary to destroy blocks in one version to make them disappear in the other.

Triple switch doors

In the Subspace Bomb Factory, there is a locked metal door with three lights on it. In the same area there are three lever-switches (blue, red, and green): hitting them sends a visible signal to the door and makes the corresponding light on it activate. Once all three switches have been activated, the three lights as well as the edge of the door will shine and the player will be able to pass.

There is also a triple switch door in The Great Maze, in an original area of The Research Facility. This door functions identically to the previous one, except that the door itself is shrouded in dark mist, indicating a Boss Battle. However, unlike the first case of such a door the three switches are located in three different rooms, instead of all being in different parts of one big room.

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  The inactive triple switch door.

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  The triple switch door with all three switches activated.

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  The shadow bugged-triple switch door.

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  An unactivated switch.

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  A switch being activated.

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  An activated switch.

Hidden doors

Hidden doors are doors that are not necessary to enter to clear a level. For example, a door might only appear right after it has been passed by, a switch must be pressed to make the door appear, or it is hidden in an unexpected place, such as where an arrow hints to go down, while the hidden door is actually above.

When a hidden door is entered, it will usually lead into a small room with a Turquoise Cube, and an Orange Cube which is harder to reach. The Orange Cube is also necessary for a higher clear %.

Special doors

Three special doors only appear after the Subspace Emissary has been completed, looking exactly like the regular red doors. Those three doors can be found in The Swamp, The Forest, and the The Ruins. When they are entered, there will be three challengers that have not appeared in the Story Mode: Jigglypuff, Toon Link, and Wolf, respectively. Defeating these characters will make them join the party and the player will unlock them, if they're not unlocked already.

In Smash Run

A door in Smash Run.

Only red doors are featured in this mode. They appear randomly across the map, and lead to special rooms where players can attempt a timed challenge for additional power-ups. Sometimes they lead to bonus rooms, with stat boosts, treasure chests, food or Iridescent Glint Beetles available without the need of a trial.

Trivia

• When a fighter enters a door, they are respawned from scratch as if a new match has started. As a result they lose all status effects, held items, and special move statuses, and Olimar will have three new Pikmin.
• When a fighter enters a door on the ground, they will walk into it. However, when fighters enter a door that is in midair, they will tumble toward it. This animation is the same as being Footstool Jumped off of.
• Through hacks, it is possible to play as Giga Bowser in the Subspace Emissary, revealing that he is incapable of using doors. As a result, without a partner to traverse doors for him, Giga Bowser can only complete levels that lack doors, those being Midair Stadium, The Ruined Hall, Battleship Halberd Bridge, and The Canyon.