Levels

Doom/Ultimate Doom

 * Knee-Deep in the Dead (sometimes called Shareware Doom)
 * The Shores of Hell
 * Inferno
 * Thy Flesh Consumed (Ultimate Doom only)

Doom II

 * Doom II

Final Doom

 * The Plutonia Experiment
 * TNT: Evilution

Heretic

 * Heretic: Shadow of the Serpent Riders

Hexen: Beyond Heretic

 * Hub 1: Seven Portals
 * Hub 2: Shadow Wood
 * Hub 3: Heresiarch's Seminary
 * Hub 4: Castle of Grief
 * Hub 5: Necropolis

Hexen: Deathkings of the Dark Citadel

 * Hexen: Deathkings of the Dark Citadel

Strife

 * Strife