Tag 666

Tag 666 is a special tag number used to denote map-specific behavior. Tag 666 is invoked not by crossing a linedef, but by killing monsters. The specific behavior is defined in p_enemy.c.

Relevant maps

Tag 666 can be used in E1M8 of Doom; E4M6 and E4M8 of Ultimate Doom; MAP07 and MAP32 of Doom II; and E1M8, E2M8, E3M8, E4M8 and E5M8 of Heretic.

Tag 666 can also be used in any Doom II WAD that contains Commander Keen figures, no matter which level they are on. Once all the Keens on a level have been killed, all sectors tagged 666 will open as blazing doors.

In Strife, tag 666 may be used in any map that contains a Spectre "E", which is the spectre spawned at the death of the Loremaster. When the spectre dies, all sectors tagged 666 will lower to the lowest surrounding floor.

Procedures

void A_KeenDie(mobj_t* mo)

This procedure is called by the death of each Commander Keen present in the level. When the last Keen dies, doors tagged 666 are opened. This procedure was used as part of an easter egg in MAP32 of Doom II. Note that this routine checks for all things of the same type as the calling monster, rather than checking for the MT_KEEN type directly, so it can easily be given to other monster types via DeHackEd.

void A_BossDeath(mobj_t *mo)

This procedure is called by the death of a boss monster. However, it only takes effect if the monster is the last of its type on the level. There are additional restrictions which differ depending on the game and level.

Doom

E1M8

Executes lowerFloorToLowest when all Barons of Hell are dead.

E2M8

No sector action: level ends when all Cyberdemons are dead.

E3M8

No sector action: level ends when all Spider Masterminds are dead.

E4M6

Executes blazeOpen when all Cyberdemons are dead.

E4M8

Executes lowerFloorToLowest when all Spider Masterminds are dead.

Doom 2

MAP07

Executes lowerFloorToLowest when all Mancubi are dead.

Executes raiseToTexture on sectors tagged 667 when all Arachnotrons are dead.

Heretic

E1M8

Executes lowerFloor when all Iron Liches are dead.

E2M8

Executes lowerFloor when all Maulotaurs are dead and kills all remaining monsters (by calling P_Massacre).

E3M8

Executes lowerFloor when D'Sparil is dead and kills all remaining monsters (redundantly since D'Sparil's death does the same thing, A_Sor2DthInit calls P_Massacre before A_BossDeath is run).

E4M8

Executes lowerFloor when all Iron Lichs are dead and kills all remaining monsters.

E5M8

Executes lowerFloor when all Maulotaurs are dead and kills all remaining monsters.

Strife

Any Map

Executes lowerFloorToLowest when all Spectre E are dead and at least one player is currently alive.

Difference in behaviour between Doom1 and Ultimate Doom

The behavior of tag 666 changed with the release of Ultimate Doom. A constraint was added which restricted tag 666 on E1M8 to triggering only on the death of the last Baron, rather than the death of any last boss monster. The classic PWAD Doomsday of UAC relied upon the deaths of both the last Baron and the last Cyberdemon to trigger it, making the PWAD unplayable in most modern source ports. The original behavior is supported in Chocolate Doom, Doomsday and PrBoom through optional compatability options, and in ZDoom, by autodetection of the level.

Specifically, the following code is responsible (A_BossDeath in p_enemy.c):

       switch(gameepisode)
       {
       case 1:
         if (gamemap != 8)
           return;

         if (mo->type != MT_BRUISER)
           return; 
         break;

The code in bold type defines the new constraint.

See also

• Tag 667

External links

• Patches for PrBoom 2.2.6 and CVS 20050820 implementing the MT_BRUISER compatibility option