Doomsday of UAC

Doomsday of UAC (commonly known by its filename UAC_DEAD) is a single-level PWAD designed by Leo Martin Lim. As part of their 10 Years of Doom feature, Doomworld named it one of the ten best WADs of 1994.

One of the first ever fan-made Doom mods, UAC_DEAD features an attempt at creating realistic-looking vehicles and environments. It contains a replacement sky graphic, and uses careful flat and texture choices in places to simulate colored lighting. It also includes the first known instance of the self-referencing sectors trick, used to simulate both invisible stairs and an invisible chamber enclosing a cyberdemon.

Walkthrough

 * Letters in italics refer to marked spots on the map. Sector numbers in boldface are secrets which count toward the end-of-level tally.

Secrets

 * 1) (sector 82)
 * 2) (sector 62)
 * 3) (sector 109)
 * 4) (sector 193)
 * 5) (sector 351)
 * 6) (sector 277)

Current records
The records for the map on the Doomed Speed Demos Archive are:

Things
Doomsday of UAC contains the following numbers of things per skill level:

Technical information
This map occupied the E1M8 slot in order to use the special tag 666 twice, exploiting a peculiarity of Doom's handling when more than one boss monster is present in the map. This peculiarity was changed in Ultimate Doom, and as the Doom source release inherited the change, the map cannot be completed with many modern source ports (because the player becomes trapped in the red key room). Chocolate Doom and PrBoom have option settings which allow the trick to operate as intended, and some versions of ZDoom identify the level through its checksum and automatically apply the correct compatibility flag.

Inspiration and development
The sky texture in this level is taken from Josh Fallon's "Nightfall" (NIGHTFAL.WAD).

Trivia
The invisible stairs are meant to be reminiscent of the film Indiana Jones and the Last Crusade.