Cleimos

Cleimos is a Doom episode replacement mod of nine levels, created by Rand and Steven Phares. It had a sequel made for Doom II, Cleimos 2.

Story
The plot revolves around a mercenary, called "Nuts" Kelton, hired to shut down the corrupted systems of a combat training center belonging to the Cleimos Corporation where the VR holograms somehow took physical life and started killing everybody. It just so happens that the holograms had been designed after the demons from Doom...

Review
This is often considered one of the best "homemade" .WADs ever created for DOOM. Where as many such .WADs are little more than mildy hacked versions of original ones, contain only a few levels at most, or are otherwise amateurish, this one is extensive, creative, and has every bit the professional, polished feel to it that the original DOOM/DOOM 2 levels had.

Levels

 * E2M1: Advent
 * E2M2: Trapped
 * E2M3: Torment
 * E2M4: Enclave
 * E2M5: Hazard Base
 * E2M6: Veil of Blood
 * E2M7: Annihilation
 * E2M8: The Ungathered
 * E2M9: Command + Control