The definitive gameplay enhancement mod for the GZDoom and Zandronum engines. Adds realistic gore, dismemberments, headshots, executions, lightning effects, particles, makes enemies smarter and harder, makes gun louder and beefier, and adds epic new boss battles.
Basically, this mod reinvents Doom in every way, and the fact that id hasn't hired SGT_Mark_IV to make Doom 4 is beyond me.