Complex Doom

Complex Doom (formerly known as Replacements) is a WAD for Zandronum by Daedalus. It features redone weapons, enemies, powerups, sounds and graphics. The most recent version is v27b2.

Legendary Complex Addon
The Legendary Complex Addon (LCA) is a WAD by Legendary that further introduces additional monsters and weapons to Complex Doom. LCA also features legendary variants of Doom's bestiary, which are extremely challenging versions of their kinds and may randomly appear throughout a level by replacing existing spawns. Upon killing a legendary monster, the player may be rewarded with legendary weapons, ammunition or powerups.