- 4 new levels: 2 normal levels & 2 secret levels
- The new Secret Levels would be accessed from Pandemonium
- Seamless ability to go between levels like in Doom:ONE, complete with "hub-style" secret exits
- Brutal Doom v20 compatibility
- Return of the Dark Claw from the original alphas
- E3M1: Hell Gate, based on the PSX map of that name. Here, remade to be massive, impressive, & have the Celestia-forsaken "gate" implied in the feathering title. In other words, redone to do the name & the game justice.
- E3M2: The Infernal Palace. Based on the PSX map titled "Hell's Keep". The level name is a homage to the version in the Lost Episode: Evil unleashed PWAD.
- E3M12: Torture Laboratory (1st secret level, access to 2nd secret level) Was originally a demo of new stuff in the Engine. Here, it's the implied "lab" accessible from E3M3. Was originally Doom Alpha v0.5 E1M1. Appears on the "Lost Episode: Evil Unleashed" Ultimate Doom PWAD as E5M1: Logos Anomaly.
- E3M13: Dante's Transit Hub (2nd secret level) The Warehouse accessible from E3M3. Was originally Doom Alpha v0.4 Map E1M11. Appears on the Evil Unleashed PWAD as E5M4: Carroll Street Station.
- Map 1: Hell Gate
- Map 2: The Infernal Palace.
- Map 3: Hell Keep
- Map 4: Slough of Despair
- Map 5: Pandemonium (1st secret level access)
- Map 12: Torture Laboratory (1st secret level, access to 2nd secret level)
- Map 13: Dante's Transit Hub (2nd secret level)
- Map 6: House of Pain
- Map 7: Unholy Cathedral
- Map 8: Mount Erebus (access to 3rd secret level)
- Map 11: Warrens (3rd secret level)
- Map 9: Gate to Limbo
- Map 10: Dis