The Lost Levels

Lost Levels is a second level campaign unlocked after beating the original campaign on Doom 64 (2020) port.

Plot
Following defeating the Mother of All Demons, Our Hero spent time tearing up hell. The Mother's sister Resurrector kicks the Marine out of hell back into a base on Earth, and tries to kill kill him. He fought his way back to Hell and takes revenge on the sister. He again chooses to fight for eternity in hell (according to developers linking Doom 64 to Doom (2016)/Doom Eternal).

Levels

 * Plant Ops
 * Evil Sacrifice
 * Cold Grounds
 * Wretched Vats
 * Thy GLory
 * Final Judgement

Fun Level

 * Panic

Ending
You had not expected to be torn from Hell so soon after your fateful decision. Getting back there was your only concern. The plans of the sister Resurrector to exterminate you have failed.

A grim vision takes hold of your mind as the demon carcasses steam in your wake. Stretched before you is a path of perpetual torment... A path through DOOM...

Behind the scenes
Lost Levels is an all new bonus campaign for Doom 64 in the vein of Doom 3: The Lost Mission, and No Rest for the Living (Doom II), and Thy Flesh Consumed (Doom)