Inferno

Inferno is the third episode in Doom/The Ultimate Doom. All of the levels in this episode are credited to Sandy Petersen, though Tom Hall originally began two of them.

This episode is set in Hell, possibly the inner region of Hell. The episode is named after Inferno, part of Dante Alighieri's Divine Comedy. The name of the final level is also a reference, as Dante describes Dis as a city encompassing the four lowest levels of Hell.

Most of these levels have a main, center room that can be easily identified, usually circular or square in shape.

Story
Now on the surface of Hell, Doomguy now has to fight his way through the main hordes of demonic forces that populate the fiery, terrifying landscape. From Imps to Cacodemons, Demons and Lost Souls, and several Barons, the Doomguy soon discovers a powerful weapon in Hell: the BFG9000. With this mighty weapon, he tears through the hellish armies as he soon reaches his way to Dis; the headquarters of the orchestrator of the demonic invasion of the Martian moons -- The Spider Mastermind. After an intense battle, the Spiderdemon is slain and Doomguy returns to Earth through a portal possibly opened by demons using Mars technology. Unfortunately, the demonic forces had already made their way to Earth, as many cities are set aflame as demons and possessed soldiers wreak havoc as Doomguy, to his horror, sees this chaos unfold as even harmless woodland creatures were slaughtered. This ending sets the stage for Doom II.

Levels

 * E3M1: Hell Keep (Petersen)
 * E3M2: Slough of Despair (Petersen)
 * E3M3: Pandemonium (Petersen and Hall)
 * E3M4: House of Pain (Petersen)
 * E3M5: Unholy Cathedral (Petersen)
 * E3M6: Mt. Erebus (Petersen; exit to secret level)
 * E3M7: Limbo (Petersen and Hall)
 * E3M8: Dis (Petersen; Spiderdemon is the boss)
 * E3M9: Warrens (Petersen; secret level)

End of Episode Message
The loathsome Spiderdemon that masterminded the invasion of the moon bases and caused so much death has had its ass kicked for all time.

A hidden doorway opens and you enter. You've proven too tough for Hell to contain, and now Hell at last plays fair -- for you emerge from the door to see the green fields of Earth! Home at last.

You wonder what's been happening on Earth while you were battling evil unleashed. It's good that no hellspawn could have come through that door with you...

Current records
The Compet-N records for the episode are: