According to McMillen’s blog there are currently 6 “dungeons,” multiple bosses and enemy types, though he hopes to expand up to 8 “dungeons” and more enemy types. The game currently has over 70 special items - not including pickup items that “can be used in different ways to acquire special items, gain access to shops and hidden areas, kill enemies and also affect gameplay in many other ways.”
During an interview with McMillen, he explained the game’s Biblical inspirations, “The game has minor biblical themes, based around Abraham going to sacrifice his son to prove to god that he believed in him – which is dark in itself. So you’ve got this kid whose mum wants to kill him, and he escapes into the basement to get away from her and eventually -maybe- conquer her.”
The game will feature a soundtrack by Danny Baranowsky (Super Meat Boy, Canabalt, Cave Story 3DS), programming by Florian Himsl (Coil, the C Word, Triachnid), and is expected to have an August 2011 release on Steam.