Perdition's Gate

Perdition's Gate is a 32-level megawad for Doom II developed by Wraith Corporation and published by WizardWorks Software in 1996. The demo version, which contained the first 11 levels, was distributed via the Internet and on D!ZONE Gold discs. Unlike its sister release, Hell to Pay (a partial conversion containing new monsters, weapons, music, and textures), Perdition's Gate only contains new music and new graphics for various textures.

According to Tom Mustaine, Perdition's Gate was offered to Id Software. He contacted Shawn Green, who "responded positively about another 32 level pack for Final Doom." Shortly afterwards, he was informed that the "Final Doom window of opportunity had closed", so Perdition's Gate was offered to Wraith Corporation instead.

Notes:

There is a discrepancy between the packing and the actual game. In the game files, the plot involves an alien invasion from outer space, while the package states that the invasion is due to an experiment gone awry.

Story as written on the package:

An experiment gone wrong, very wrong... a scientific genetics engineering plant has been taken over by those very mutants it created. You must find out what happened... and the onlay way to do that is to fight the monsters to the death.

The ultimate test of your skill, wit and personal character.