The three keycards, the skull keys, and the corresponding status bar icons.

A key is an item used to open designated locked doors or switches.

Description

The yellow skull key as seen in MAP28 of Doom II

There are two types of key: electronic keycards, and skull keys which resemble glowing monochrome skulls. Generally, techbase levels feature keycards and hellish levels feature skull keys. If the player encounters a locked door and attempts to open it without the correct key, the door will not open (and the player will receive a message to that effect). Once a key is obtained, any locked door of the corresponding color on the map can be opened. All keys are lost upon exiting a map or respawning after death in co-op mode.

Multiple keys of a given color may be picked up in the same level; the status bar will display whichever type was last taken. Doors in vanilla Doom are affected identically by keycards and skull keys. In stock maps, as a cosmetic guideline, a bar of coloured lights surround a locked door when keycards are used, while a column of coloured skulls are used for skull keys. (However, this is occasionally violated, such as in E2M3: Refinery which had keycard pickups but skull doorframes.)

In multiplayer deathmatch games, all keys are removed from each map, and players spawn carrying all keys.

Enhancements

  • Ultimate Doom and Final Doom introduced "locked" switches, which cannot be activated without a key of the appropriate color. The feature, however, was limited only to buttons that open fast doors permanently. Such switches were already supported in Doom II but the level designers never used them in the game, except as "locked fast open door" without a "switch".
  • Boom introduced door types that require the key to be of the right type and not just the right color. Such doors are supported in most source ports.
  • Certain source ports also allow the use of locked doors requiring multiple keys, a situation sometimes approximated in the original games by placing several locked doors in front of each other (e.g. E2M6: Halls of the Damned). Another notable example of this phenomenon appears in MAP29: For We Are Many of Community Chest 3: the door to the level exit has all three skull key indicators flanking it, and the message, "You need all three keys to open this door," will appear if a player who does not possess all three keys tries to open the door. MAP19: The Citadel has a feature where the exit has three shafts, each with a different key type however in this case only 2 certain shafts of the three need to be opened as opposed to all three. MAP09: Abattoire also has that feature, but only the red keycard shaft needs to be opened. All three keys are still required in this case.
  • Doom 64 introduced a key-activated, or "locked", tripwire in MAP30: The Lair; the player needs to be in possession of the yellow key and pass through the tripwire in order to lower a switch on the wall. If the player does not possess the key the switch will not lower, the Marine will "Mmmph!" and the line "You Need The Yellow Key" will appear on the top of the screen.
  • In the Playstation Ports and Doom 64, locked doors often have coloured lighting corrosponding to the key's color and when attempting to open a door without the key, will not only produce the "Omph" and the message but the key's icon will flash a few times in the HUD.
  • Doom 3 features some keycards, but they do not have a color associated with them and they are less common, more like unique puzzle items rather than a regular feature, and skull keys do not exist. More often, the UAC facility is depicted as locking down sections due to demonic infestations, requiring the player to kill monsters or do some other task to access them.
  • Doom (2016) reintroduces keycards and skull keys in the classic Doom sense. The main difference is that only yellow and blue are featured, with red not shown presumably because various offline doors in the UAC complex are indicated using red. They are also shown with more real-life context, with keycards shown being recovered from the bodies of dead UAC employees, whereas the skulls are found floating above pedestals. The skull key also now features its own animation when it is actually being used, operating by being inserted into a recess on the door that it opens. Doom also borrows methods from Doom 3 of locking parts of maps, including the "lockdown" method of keeping a part of a map inaccessible until the monsters in a given area are killed. Because of this, keys are still not as common as in Classic Doom, and most levels will feature only one key, or even none at all.

Data

The yellow keycard in MAP02 of Alien Vendetta

The red skull key in MAP09 of Alien Vendetta

Blue keycard data
Thing type 5 (decimal), 5 (hex)
Appears in Shareware Doom
Registered Doom
Ultimate Doom
Doom II/Final Doom
Radius 20
Sprite BKEY
Class Key
Pickup

The red keycard in MAP02 of Alien Vendetta

Red keycard data
Thing type 13 (decimal), D (hex)
Appears in Shareware Doom
Registered Doom
Ultimate Doom
Doom II/Final Doom
Radius 20
Sprite RKEY
Class Key
Pickup
Yellow keycard data
Thing type 6 (decimal), 6 (hex)
Appears in Shareware Doom
Registered Doom
Ultimate Doom
Doom II/Final Doom
Radius 20
Sprite YKEY
Class Key
Pickup

The blue skull key in E4M1 of Doom

The blue keycard in ATTACK.WAD from the Master Levels

Blue skull key data
Thing type 40 (decimal), 28 (hex)
Appears in Registered Doom
Ultimate Doom
Doom II/Final Doom
Radius 20
Sprite BSKU
Class Key
Pickup
Red skull key data
Thing type 38 (decimal), 26 (hex)
Appears in Registered Doom
Ultimate Doom
Doom II/Final Doom
Radius 20
Sprite RSKU
Class Key
Pickup
Yellow skull key data
Thing type 39 (decimal), 27 (hex)
Appears in Registered Doom
Ultimate Doom
Doom II/Final Doom
Radius 20
Sprite YSKU
Class Key
Pickup

Appearance statistics

The IWADs contain the following numbers of keys:

Blue keycard

Game ITYTD and HNTR HMP UV and NM
Ultimate Doom 11 11 11
Doom II 14 14 14
TNT: Evilution 17 17 17
Plutonia 11 11 11

Red keycard

Game ITYTD and HNTR HMP UV and NM
Ultimate Doom 7 7 7
Doom II 11 11 11
TNT: Evilution 18 18 18
Plutonia 7 7 7

Yellow keycard

Game ITYTD and HNTR HMP UV and NM
Ultimate Doom 9 9 9
Doom II 9 9 9
TNT: Evilution 14 14 14
Plutonia 8 8 8

Blue skull key

Game ITYTD and HNTR HMP UV and NM
Ultimate Doom 15 15 15
Doom II 8 8 8
TNT: Evilution 8 8 8
Plutonia 11 11 11

Red skull key

Game ITYTD and HNTR HMP UV and NM
Ultimate Doom 12 12 12
Doom II 8 8 8
TNT: Evilution 10 10 10
Plutonia 12 12 12

Yellow skull key

Game ITYTD and HNTR HMP UV and NM
Ultimate Doom 11 11 11
Doom II 8 8 8
TNT: Evilution 8 8 8
Plutonia 14 14 14


In the 2016 Doom reboot, only blue and yellow are used, although red can appear in the Classic Maps. Each combination of blue or yellow, and keycard or skull, occur exactly three times in the game:

Key appearances in Doom (2016)
Blue keycard The UAC
Foundry
VEGA Central Processing
Yellow keycard Resource Operations
Foundry
Argent Facility (Destroyed)
Blue skull
Yellow skull
Kadingir Sanctum
Titan's Realm
The Necropolis

Doom RPG

Keycards appear in Doom RPG, but skull keys do not.

See also

External links

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