NOTE: All files are - to my knowledge -  the latest versions available. If you know of a later version, please let me know. I'd also like to know about any new tools that you think are worthwhile, and I'll definitely try them out. Please report any broken links.  *updated 05-07-04

*Doom Builder: An Illustrated Guide Version 1.1 by John W. Anderson. 144 pages. Manual for the level editor, Doom Builder. Illustrated with over a hundred screenshots, this manual has three sections covering the Doom Builder interface, step-by-step instructions on using the editor to build levels, and advanced functions. Updated 05.07.04, revised, and expanded to 144 pages.

ADOBE ACROBATPDF
  2.2MB  DBGUIDEP.EXE
 MS Word Document
   4.3MB  DBGUIDE.EXE
  

*WinDEU for Beginners v1.1 by Dr Sleep. Step-by-step pictorial guide to basic editing using WinDEU v5.24. Explains the WinDEU interface, hotkeys, and building a small level step-by-step. (Also viewable online in the Tutorials section.) Self-extracting archive. Updated 04.10.04, revised, and expanded to 91 pages.

MICROSOFT WORD
  1.89MB  WDEUGUIDE.EXE
 HTML
   880k      WDEUGUIDEH.EXE
 ADOBE ACROBAT PDF
   843k      WDEUGUIDEP.EXE 

The Unofficial DOOM Specs v1.666 by Matt Fell. The ultimate reference guide to technical aspects of DOOM; required reading for level designers.

  ASCII TEXT
  60k   DMSPEC16.ZIP
          DMSPEC16.TXT

The Official DOOM FAQ v1.666 by Hank Leukart. Everything you've always wanted to know about DOOM but were afraid to ask.

  ASCII TEXT

  123k  DMFAQ66.ZIP

*WAD Author's DOOM Reference v1.0 by Jim Flynn. Text (or HTML) reference to all special LineDef action types (raise floor, open door, etc.), Sector Types, and Thing types, meticulously researched and laid out by Function and Number. Also includes design tips on using special actions and tags. Level designer's dream. (Also viewable online in the Tutorials section.) Self-extracting archives.

  ASCII TEXT
    23k    DOOMREFR.ZIP
             DOOMREFR.TXT
  HTML
   126k   DOOMREFRH.EXE
   ADOBE ACROBAT PDF
   327K  DOOMREFRP.EXE
  MICROSOFT WORD
   141K  DOOMREFRD.EXE

*Texture Management: The Unpegged Attribute and Texture Aignment by Dr Sleep. This is Part One of a section on textures that explains how DOOM renders texture maps, plus how the unpegged attribute for upper and lower textures works; also, how to use the lower unpegged flag to advantage with normal textures. Illustrated with color texture examples showing various methods of unpegging and alignment.

*Speed Up Your Level: Optimizing the REJECT Resource and Other Tricks by Dr Sleep. This article explains how the REJECT resource works, the hows and whys of the DOOM engine's line-of-sight calculations, and special tricks to create special effects in your levels such as creating Sectors where monsters are blind or players can't be seen.

Hacking the DOOM EXE by Matt Fell. This ZIP file contains this early article by the author of The Unofficial DOOM Specs, as well as five Qbasic programs for printing resources in the DOOM.EXE that are talked about in the article.

  ASCII TEXT
  15k   DEHACKER.ZIP
          DEHACKER.TXT

DOOM Metrics by Scott Amspoker. Height, width, radius, and step measurements for all enemies and players. Vital for knowing whether that Caecodemon will fit through the door or window.

  ASCII TEXT
  4k     METRICS.ZIP
          METRICS.TXT

Design FAQ v1.2 Frequently Asked Questions About DOOM Level Design by Tom Neff. Includes "10 Most Common Design Errors" and other practical advice on level design.

WAD Authoring Template v2.0. This is the standard text file used by nearly all level designers to describe their level (and give information about themselves). It should accompany your WAD in the ZIP release.

The Unofficial HERETIC Specs (released anonymously by American McGee). The first list of Sector, Thing, and LineDef specials.

HERETIC LineDef Action Type Reference v1.1a by John W. Anderson (aka Dr Sleep). Text reference to all the LineDef action types as well as Sector specials (wind, friction, scrolling, etc.) and Thing types.