The Ultimate Doom is the upgraded version of Doom which adds a fourth episode to this brilliant game. Doom is perhaps one of the most influential games to grace PCs around the world and is often cited as being the greatest video game of all time.

In the Ultimate Doom you play a space marine, Doomguy, who must battle his way through 36 levels and destroy the four Guardians of Hell. Each episode has a secret level. You can find the exit for each one hidden in one of the main levels.

The Ultimate Doom Walkthrough

Episode 1: Knee-Deep in the Dead

Mission 1: Hangar
Mission 2: Nuclear Plant
Mission 3: Toxin Refinery (Exit to Secret Level)
Mission 4: Command Control
Mission 5: Phobos Lab
Mission 6: Central Processing
Mission 7: Computer Station
Mission 8: Phobos Anomaly
Mission 9: Military Base (Secret Level)

Episode 2: The Shores of Hell

Mission 1: Deimos Anomaly
Mission 2: Containment Area
Mission 3: Refinery
Mission 4: Deimos Lab
Mission 5: Command Center (Exit to Secret Level)
Mission 6: Halls of the Damned
Mission 7: Spawning Vats
Mission 8: Tower of Babel
Mission 9: Fortress of Mystery (Secret Level)

Episode 3: Inferno

Mission 1: Hell Keep
Mission 2: Slough of Despair
Mission 3: Pandemonium
Mission 4: House of Pain
Mission 5: Unholy Cathedral
Mission 6: Mt. Erebus (Exit to Secret Level)
Mission 7: Gate to Limbo
Mission 8: Dis
Mission 9: Warrens (Secret Level)

Episode 4: Thy Flesh Consumed

Mission 1: Hell Beneath
Mission 2: Perfect Hatred (Exit to Secret Level)
Mission 3: Sever the Wicked
Mission 4: Unruly Evil
Mission 5: They Will Repent
Mission 6: Against Thee Wickedly
Mission 7: And Hell Followed
Mission 8: Unto the Cruel
Mission 9: Fear (Secret Level)