One level (map31) for limit removing ports. This map contains 39114 sidedefs, so you need port which can handle more than 32767 sidefs. PrBoom-Plus or GZDoom are recommended.
id Software, of course. Also the authors of DoomBuilder, DeePsea and DeuTex. And thanks to entryway, Heretic and Hitherto for beta-testing. Some textures are from Heretic and Hexen. Sky texture is from Hell Revealed.