The New Genesis Stages
A set of new stages; effectively an alternate "campaign". For info on the new enemy types and bosses, see my submissions in Fan Ideas/Enemies and Fan Ideas/Bosses.
The Boiler Room
Two sets of floors with a steam-punky motif to them, serving as the first floors of this new scenario. You'll find generic enemies from the Cellar and Basement in here, mostly Clots, Trites and Spiders. Bosses that can be found on these floors are: Monstro, Widow, Gurdy.Jr, Famine, The Fallen and Headless Horseman. Rusted tiles can be found in rooms. These will hurt you for half a heart when walked over, but do not hurt enemies.
The next two set of floors, set in a dark-ish underground tunnel system, like the Caves but a lot more gritty and with patches of vegetation in places. Enemies from Catacombs and Caves can be found here, with a focus on Blockages, Super Pooters and Hosts. Leeches can be found rarely as well. Bosses fought in these floors range from: The Husk, Chub, Blighted Ovum, Pestilence, The Fallen and Headless Horseman. Shrubs can be found throughout the Subterra; these can be destroyed with a chance of dropping hearts. If the player has the Candle, they can light the shrubs, effectively turning them into fires. New enemies include Vomit Pooters.
These floors follow a much more stoney theme, with various bones across scattered across the floor and gothic aspects in scenery. Enemies from the Depths and Necropolis can be found within, but most enemies found will range between Globins, Knights and Swarmheads. Turrets are also common here. Bosses found down here can be: Scleteris, Mask of Infamy, The Bloat, War, The Fallen and Headless Horseman. Brittle rocks can be found in the Crypt; they can be destroyed with a few tear shots. These rocks cannot drop items, but can make bridges across gaps. New enemies include Boneheads and Pilferers.
A darker grey set of floors with a more polished texture to them, but random spats of blood and other fluids in places too. Enemies from the Necropolis can be found here, and certain ones from the Utero and Womb, including Leeches, Eyes and Knights. The Seven Sins can appear as room mobs, as well as versions of Larry Jr., Monstro and Pin. Bosses found within these parts include: Lokii, Triachnid, any one of the 7 Demons of Sin, Death, The Fallen or the Headless Horseman. Spike trap tiles can be found throughout the Mausoleum. These occasionally raise up spikes that hurt for one heart of damage. Players take one heart of damage throughout these levels. New enemies include Boneheads and Marrows.
A single floor that consists of whitish grey walls with dark grey floors. While the walls are angelic themed, the floors are more death-like. Consists of only 8 rooms, including an unlocked Treasure Room that contains 2 free items. Enemies encountered in this place can be any of the 7 Demons of Sin or the Four Horsemen (Including the Headless Horsemen). The boss fought in this final level is Simon.