Key

This article is about the keycards and skulls found as in-game items. For the keys used for moving, shooting, etc., see Controls.

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

Description

The first key encountered in the series, a red keycard in E1M2: Nuclear Plant from the Knee-Deep in the Dead episode of Doom

There are two types of key: electronic keycards, and skull keys which resemble glowing monochrome skulls. 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.

Multiple keys of a given color may be picked up in the same level; the status bar will display whichever type was last taken, but if the player already has the skull key and picks up a key card, the skull key remains in the display and if the player picks up the key card and then picks up the skull key, the skull key is displayed. 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 Doom's E2M3: Refinery which had keycard pickups but skull doorframes.)

Keys, as other things, can be flagged to appear on certain skill levels. This allows the map designer to place a key in a more challenging spot for higher levels of difficulty. The original games include a couple of instances. In Doom's E3M6: Mt. Erebus, the blue skull key can be found quite effortlessly in the center area when playing on the easiest levels. If played on Hurt Me Plenty or higher, the key is instead hidden inside one of the buildings. Thus, in addition to being attacked by a larger population of monsters, the player also has to explore more areas to find the key. In Doom II's MAP06: The Crusher, the blue keycard will appear at one of three possible locations in the great crusher hall. The higher the skill level, the bigger effort the player has to make to obtain the key.

In multiplayer deathmatch games, all keys are removed from each map, and players spawn carrying all keys, shown as skull keys on the status bar.

Enhancements

• Ultimate Doom and Final Doom introduced "locked" switches, which cannot be activated without a key of the appropriate color. However, the feature was limited only to toggles that open fast doors permanently. Such switches were already supported in Doom II but the level designers never used them in the game.
• Boom introduced door types that require the key to be of the right type and not just the right color, such as a door that responds to a red skull but not to a red keycard. Boom also introduced locks requiring all 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), and locks requiring any key. In Boom and compatible ports (that is, most ports), a locked door can be activated in any way a linedef can (including walkover) and can have any movement speed and delay before moving back (or staying in the final position) supported by Boom.
• Hexen replaced hardcoded linedef types (e.g., 26 for blue key, 27 for yellow, 28 for red) by action specials where the key is represented by a parameter, making it simpler to manage the eleven key types from the game. In addition to door specials, Hexen also allows ACS trigger specials to be locked in the same manner. ZDoom extended the parameterized system to allow mappers to define new lock types with the LOCKDEFS lump, enabling the creation of doors requiring any arbitrary key combination.
• Doom 64 changed the key system to be entirely independent of line type, instead being a property of the linedef itself. This allows to use key locks on any line type; for example there is a "locked" tripwire in MAP30: The Lair, which lowers a switch on the wall when traversed, but only if the player has the yellow key. If the player does not possess the key the switch will not lower, the marine will grunt, and the line "You Need The Yellow Key" will appear at the top of the screen. In addition, the game will make the appropriate key icon in the status bar flash for a short while when trying to activate a locked line without the proper key, a feature it shares with the PlayStation version of Doom.

Data

The blue keycard in ATTACK.WAD from the Master Levels.

The blue keycard found in MAP29: Outpost Omega from Doom 64.

Blue keycard data
Thing type	5 (decimal), 5 (hex)
Enum	MT_MISC4 (47) - Doom MT_ITEM_BLUECARDKEY (51) - Doom 64
Appears in	Shareware Doom Doom/Ultimate Doom Doom II/Final Doom Doom 64/Lost Levels
Radius	20
Height	16
Sprite	BKEY
Frames	2 [AB] - Doom 2 [AA] - Doom 64
Class	Key Pickup
Flags	33554433 (decimal) 02000001 (hex)
Flags list	0: Can be picked up 25: Not in deathmatch

The red keycard in MAP03: Chambers of Confusion of Obituary.

The red keycard in MAP05: Tech Center from Doom 64.

Red keycard data
Thing type	13 (decimal), D (hex)
Enum	MT_MISC5 (48) - Doom MT_ITEM_REDCARDKEY (52) - Doom 64
Appears in	Shareware Doom Doom/Ultimate Doom Doom II/Final Doom Doom 64/Lost Levels
Radius	20
Height	16
Sprite	RKEY
Frames	2 [AB] - Doom 2 [AA - Doom 64
Class	Key Pickup
Flags	33554433 (decimal) 02000001 (hex)
Flags list	0: Can be picked up 25: Not in deathmatch

The yellow keycard in MAP02: Rusty Rage of Alien Vendetta.

The yellow keycard in MAP07: Research Lab from Doom 64.

Yellow keycard data
Thing type	6 (decimal), 6 (hex)
Enum	MT_MISC6 (49) - Doom MT_ITEM_YELLOWCARDKEY (53) - Doom 64
Appears in	Shareware Doom Doom/Ultimate Doom Doom II/Final Doom Doom 64/Lost Levels
Radius	20
Height	16
Sprite	YKEY
Frames	2 [AB] - Doom 2 [AA] - Doom 64
Class	Key Pickup
Flags	33554433 (decimal) 02000001 (hex)
Flags list	0: Can be picked up 25: Not in deathmatch

The blue skull key in MAP26: Between Scattered Corpses of Memento Mori.

The blue skull key in MAP16: Blood Keep from Doom 64.

Blue skull key data
Thing type	40 (decimal), 28 (hex)
Enum	MT_MISC9 (52) - Doom MT_ITEM_BLUESKULLKEY (56) - Doom 64
Appears in	Doom/Ultimate Doom Doom II/Final Doom Doom 64/Lost Levels
Radius	20
Height	16
Sprite	BSKU
Frames	2 [AB] - Doom 2 [AA] - Doom 64
Class	Key Pickup
Flags	33554433 (decimal) 02000001 (hex)
Flags list	0: Can be picked up 25: Not in deathmatch

The red skull key in MAP16: Castle of Evil of The World of Deth: From Heaven To Hell.

The red skull key in MAP20: Breakdown from Doom 64.

Red skull key data
Thing type	38 (decimal), 26 (hex)
Enum	MT_MISC8 (51) - Doom MT_ITEM_REDSKULLKEY (55) - Doom 64
Appears in	Doom/Ultimate Doom Doom II/Final Doom Doom 64/Lost Levels
Radius	20
Height	16
Sprite	RSKU
Frames	2 [AB] - Doom 2 [AA] - Doom 64
Class	Key Pickup
Flags	33554433 (decimal) 02000001 (hex)
Flags list	0: Can be picked up 25: Not in deathmatch

The yellow skull key in MAP27: Terror of Scythe.

The yellow skull key in MAP32: Hectic from Doom 64.

Yellow skull key data
Thing type	39 (decimal), 27 (hex)
Enum	MT_MISC7 (50) - Doom MT_ITEM_YELLOWSKULLKEY (54) - Doom 64
Appears in	Doom/Ultimate Doom Doom II/Final Doom Doom 64/Lost Levels
Radius	20
Height	16
Sprite	YSKU
Frames	2 [AB] - Doom 2 [AA] - Doom 64
Class	Key Pickup
Flags	33554433 (decimal) 02000001 (hex)
Flags list	0: Can be picked up 25: Not in deathmatch

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	19	19	19
Plutonia	11	11	11
Doom 64	13	13	13
The Lost Levels	1	1	1

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
Doom 64	6	6	6
The Lost Levels	1	1	1

Yellow keycard

Game	ITYTD and HNTR	HMP	UV and NM
Ultimate Doom	9	9	9
Doom II	9	9	9
TNT: Evilution	13	13	13
Plutonia	8	8	8
Doom 64	9	9	9
The Lost Levels	1	1	1

Blue skull key

Game	ITYTD and HNTR	HMP	UV and NM
Ultimate Doom	15	15	15
Doom II	8	8	8
TNT: Evilution	7	7	7
Plutonia	11	11	11
Doom 64	15	15	15
The Lost Levels	4	4	4

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
Doom 64	13	13	13
The Lost Levels	5	5	5

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 64	16	16	16
The Lost Levels	4	4	4

Doom RPG

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

See also

• Heretic keys
• Hexen keys
• Strife keys
• Hacx keys
• Doom Eternal keys
• Monsters open locked doors

External links

• The Doom II Key FAQ at Doomworld/idgames
• Doom RPG FAQ by Tony8669, at gamefaqs.com