The Plutonia Experiment

The Plutonia Experiment is an IWAD released I don't know when is one half of Final Doom.

Development
Brothers Dario and Milo Casali, who had contributed four levels to TNT: Evilution, were assigned the the task of creating what became Plutonia after having sent an 8-level WAD they had created to American McGee and managing to impress him along with the rest of the id Software crew. They created 16 levels each for Plutonia in four months time, and submitted them in January 1996. Unlike their contributions to TNT: Evilution, which were edited after submission (four were also rejected due to being too large), these were the final revisions of the levels, and Dario Casali later commented about the fact that no changes were requested, "thank God because I was ready to throw my computer out the window at the time".

Story
After hell's catastrophic invasion of Earth, the global governments decide to take measures against any possible future invasion, knowing that the powers of Hell still remained strong. The UAC corporation is refounded under completely new management (the old trustees and stockholders were all dead anyway) and aims at developing tools that would prevent demonic invasions.

The scientists start working on quantum accelerator devices that are intended to close invasion gates and stop possible invasions. The experiments are carried out in a secret research complex, with a stationed detachment of marines. The work seems to be going well but...

The creatures form outside have their dire attention drawn towards the new research. A gate opens in the heart of the complex and unnatural horrors pour out. The quantum accelerator performs superbly - the gate is quickly closed and the invasion stopped. Research continues more boldly.

On the next day, a ring of 7 gates opens and an even greater invasion begins. For 1 hour the quantum accelerators manage to close 6 of the gates... but the hellish army has become too numerous and too strong. The complex is overrun. Everyone is slain, or zombified. The last gate of hell remains open, manned and guarded by a demon Gatekeeper.

The government, frantic that the quantum accelerator will be destroyed or used in some evil alien fashion against humanity, orders all marines to the site at once. The player was close to the site and goes there first. There he discovers that there is much demonic activity (howling, chanting, machine sounds) within the comlex - the Gatekeeper is obviously working on something, and his work would soon reach some awful climax. He also realizes that when the marines arrive, they would not be able to penetrate the heavily infested complex, and will all be slain.

The marine decides to enter the complex and stop the Gatekeeper alone.

Levels

 * Plutonia MAP01: Congo
 * Plutonia MAP02: Well of Souls
 * Plutonia MAP03: Aztec
 * Plutonia MAP04: Caged
 * Plutonia MAP05: Ghost Town
 * Plutonia MAP06: Baron's Lair
 * Plutonia MAP07: Caughtyard
 * Plutonia MAP08: Realm
 * Plutonia MAP09: Abattoire
 * Plutonia MAP10: Onslaught
 * Plutonia MAP11: Hunted
 * Plutonia MAP12: Speed
 * Plutonia MAP13: The Crypt
 * Plutonia MAP14: Genesis
 * Plutonia MAP15: The Twilight
 * Plutonia MAP16: The Omen
 * Plutonia MAP17: Compound
 * Plutonia MAP18: Neurosphere
 * Plutonia MAP19: NME
 * Plutonia MAP20: The Death Domain
 * Plutonia MAP21: Slayer
 * Plutonia MAP22: Impossible Mission
 * Plutonia MAP23: Tombstone
 * Plutonia MAP24: The Final Frontier
 * Plutonia MAP25: The Temple of Darkness
 * Plutonia MAP26: Bunker
 * Plutonia MAP27: Anti-Christ
 * Plutonia MAP28: The Sewers
 * Plutonia MAP29: Odyssey of Noises
 * Plutonia MAP30: The Gateway to Hell
 * Plutonia MAP31: Cyberden
 * Plutonia MAP32: Go 2 It