Another hero visits the ground zero site in Switzerland, a few changes have occured.
ID Games for doom BRPD for the sky (used in Map24 of CChest2) The artists/games/tv shows for which the music for this wad comes from. The People from doomworld who actually tested this and helped to implement better gameplay.
New from scratch
Doom builder 2 and Slade 3
Not any I have found. There are likely to be visplane overflows in Vanilla.