Every Doom engine game uses the same header and directory, the same picture format and the same flats. They differ in which lumps they have, in some lumps’ layouts and in what the numbers inside mean. Nothing in a WAD’s header says which game it is for: an IWAD is known by the lumps it holds, and a PWAD usually only by its maps and the thing types in them.
At a glance
| Doom | Doom II | Heretic | Hexen | Strife | |
|---|---|---|---|---|---|
| Year | 1993 | 1994 | 1994 | 1995 | 1996 |
| Map names | E1M1 to E4M9 | MAP01 to MAP32 | E1M1 and on | MAP01 and on | MAP01 and on |
| Map format | Doom | Doom | Doom | Hexen (with BEHAVIOR) | Doom |
| Texture layout | Doom | Doom | Doom | Doom | Strife |
| Translucency | none | none | TINTTAB | TINTTAB | XLATAB |
Doom and Doom II
Doom’s maps come in episodes of nine, E1M1 to E3M9, and
The Ultimate Doom adds a fourth episode and DEMO4. The shareware
DOOM1.WAD holds only the first episode. Doom II has one run of maps,
MAP01 to MAP32, new monsters and weapons, and only
TEXTURE1. Final Doom’s TNT: Evilution and The Plutonia Experiment are
Doom II IWADs. Both games use 14 palettes, 34 colour maps, DMX sounds named
DS and DP, and MUS songs named D_.
Heretic
Raven Software’s Heretic keeps Doom’s map format, but its thing numbers mean other
things: only the player starts 1 to 4 and the deathmatch start 11 are the same. Its
quit screen is ENDTEXT, its songs start MUS_, its sound lumps
have names of their own, and it adds the translucency table TINTTAB. Some
of its full-screen pictures are raw 320 × 200 lumps.
Hexen
Hexen has its own map format: things with an ID, a height, a special and five
arguments; lines whose special has five arguments and whose flags say how it is set
off; and a BEHAVIOR lump of compiled ACS scripts for each map. Text lumps
such as MAPINFO, SNDINFO and ANIMDEFS name the
maps, the sounds and the animations that Doom had built into its program. Its
PLAYPAL has more palettes than Doom’s, and FOGMAP is a
second set of colour maps. The map lumps
page gives the layouts.
Strife
Rogue Entertainment’s Strife uses Doom’s map format with its own thing numbers and
line specials, a shorter texture
layout, the translucency table XLATAB and the quit screen
ENDSTRF. Its conversations are in SCRIPT lumps, one for each
map, in a binary format this reference does not cover.
Telling them apart
The explorer names an IWAD’s game from its lumps: ENDSTRF means Strife,
maps with BEHAVIOR mean Hexen, ENDTEXT means Heretic, and
ENDOOM with MAP01 or E1M1 means Doom II or Doom.
For a PWAD it names no game. It draws every map the same way, and names things only for
maps in Doom’s format, with Doom’s names, since most PWADs are for Doom; in a Heretic
or Strife PWAD those names are wrong.