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

Description

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 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 (although, red keys are still featured in Classic Doom maps). 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.

• Doom Eternal de-emphasizes keys, with a greater reliance on separating different parts of the levels. In fact, except for the special Slayer Keys, they never appear after the Super Gore Nest. The Slayer Keys in six of the levels are used to unlock the Slayer Gates, which upon completion award Empyrean Keys that can be used to unlock the Unmaykr in the Fortress of Doom.

Data

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

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

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

Doom 3

In Doom 3 and its expansions, rather than having identical keys across levels, all of the keys or assorted items are unique, and not found in other levels with one exception. PDAs also take the place of many keycards, so physical keys aren’t as common.

• ACO Keycard: The first keycard you get, it is quite easy to find and easily accessible. It’s also essentially right next to the door it unlocks. Found in the room Reception Processing of Mars City Revisited.

• Maintenance Key 4: It‘s the key you have to do the crane puzzle for. It’s also a hallway down from its door. Found in Hazardous Waste Management room in Alpha Labs Sector 3.

• Data Linker: You need this to restart the reactor and start the power in the whole Delta Complex. It’s found next to a corpse in Delta 1 Access Lobby in Delta Labs Sector 1.

• Plasma Inducer: Dr. Ian McCormick needs this to power up the teleporter to enter Sector 2B. It is found in Operations Server Room in Delta Labs Sector 2A. Another one is needed in The Lost Mission. Your chase for this lasts for two levels, being Exis Sector 1 and Sector 2. Found in Molecular Engineering Lab.

• BRD Access Card: Found at the start of the level, it’s in a observation room next to a devious guy who pretends to be dead but isn’t. It’s also practically on top of it’s door. Found in the Teleport Observation room in Delta Labs Sector 2B.

• D-Lib Replacement Panel: Instead of having to unlock a door or simply being locked and not having a way to unlock it or just being broken entirely. This door needs the panel to be replaced, and you have to go through the whole level to get it. It’s in a cabinet, and once you get it, a plethora of monsters will spawn in. Found in Lab A Upper Floors in Central Processing.

• Caverns Access: A door in the Caverns Area is locked under Mars City. Climb down the platforms moving in and out before reaching a survivor and grabbing the keycard. Found in Thermal Regulation Pump in Caverns Area 1.

• Storage Room 11 Key: Completely optional, after killing the trio of deadly enemies in the first room, you’ll notice one door needs a key. After going through the tunnel with Wraiths, and entering the large, open room before the Temple, on a table you will see a keycard. Going back and unlocking the door will grant you two Plasma Cells, a Grenade Pack, a BFG Cell, a small Shell Box, a Rocket Box, and some clips along with a health station. Found in Main Excavation in Caverns Area 2.

• Power Cell: These things are found everywhere in the first four levels of Resurrection of Evil and in Underground Sector 1 in The Lost Mission. You essentially just take it out of its compartment and move it into another one to power stuff up.

• Administration: This key is found in Sarge’s Super Shotgun cabinet. Its according room is the room directly next to it containing a power cell. Found at Sarge’s Office in Erebus Level 3.

• The Primitive: It’s a stone tablet that has information on it about the Artifact. You trade it with a scientist for a keycard to the Armory in the best lunchtime trade of all time in Erebus Level 5. Found in Artifact Storage in Erebus Level 3.

• Armory Access: You get this in a cutscene, you essentially trade your stuff with a scientist like you’re at the lunch table. It gives you access to the armory, where you get the Chaingun before the Waste Tunnels. Found in Erebus Level 5.

• Skytram Access: You get it in order to access the Skytram, not much else. Found in Utility Closet in Phobos Labs Sector 1.

• Pumping Station: Elizabeth McNeil gives you it in a cutscene so you can shut down some stuff. Found in Phobos Labs Sector 2.

• Reactor Key: To shut down the reactor, you have to go into the Reactor Control room. The key is found in the near bottom of the reactor core in a maintenance area. Found in Upper Maintenance in Phobos Labs Sector 3.

• SSD Drive: In Enpro Sector 1, Dr. Richard Meyers gives you this key at the end of the level to send power over to Exis. You do this in Sector 2.

• Keycard: This very specifically named key is found next to a dead body on a bench. It is the main wild goose chase of the level, with the locked door being in the beginning of the level. Found in Transfer Control in Underground Sector 1.

Doom (2016)

In the 2016 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
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 Eternal

In Doom Eternal, keys are rare overall, except for the Slayer Keys.

Key appearances in Doom Eternal
Yellow keycard	Hell on Earth
Cultist key	Cultist Base
Red keycard	Doom Hunter Base UAC Atlantica Facility
Blue keycard	UAC Atlantica Facility
Blue gore key Red gore key Yellow gore key	Super Gore Nest
Slayer key	Exultia Cultist Base Super Gore Nest ARC Complex Mars Core Taras Nabad UAC Atlantica Facility The Holt

Doom RPG

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

See also

• Hexen keys
• Strife keys
• Monsters open locked doors

External links

• The Doom II Key FAQ, at doom2.net
• Doom RPG FAQ by Tony8669, at gamefaqs.com

Doom Items Health Health bonus Stimpack Medikit Armor Armor bonus Armor Megaarmor Weapons Fist Chainsaw Pistol Shotgun Chaingun Rocket launcher Plasma gun BFG9000 Added in Doom II Super shotgun Added in Legacy of Rust Incinerator Calamity blade Added in Doom v0.2, Doom v0.3 Bayonet Assault rifle (Doom) Dark Claw BFG 2704 Ammo Backpack Clip 4 shotgun shells Rocket Energy cell Box of bullets Box of shells Box of rockets Energy cell pack Items Key Powerups Berserk Computer area map Invulnerability Light amplification visor Partial invisibility Radiation shielding suit Soul sphere Added in Doom II Megasphere