Abaddon is a series idea I had where there are six games created in a universe where wolfenstein 3d, the doom series, the raven spin-offs, and quake never existed.
I have here a level from abaddon 3, the doom 2 replacement. Instead the entire first person shooter genre would not have existed if it weren't for these gems.
I also created this website to explain what will take the place of what.
The Wolfenstein 3-D hack Abaddon 1 would be mostly red hell walls and a cheezy story about how a family moved into a new house and a kid stumbled upon an opening in the basement to a multi-level "hell dungeon."
The Doom 1 hack would feature vanilla levels and the first doom's enemy cast. Abaddon 3 would be Doom 2, with new ACS Scripting here and there but nothing big. Abaddon 4 would be for Heretic while Abaddon 5 would be for Hexen.
Abaddon 666 was going to be a quake mod made within Doom in the Hexen format, so that slopes would be possible and floors above floors but I wasn't exactly going to attempt to mod for Quake, which is apparently one of the hardest things to do.