From an older time in history came Gloom. Clearly styled as a Doom clone, but for the Amiga, Gloom had 3 games released, with Gloom Deluxe being one of the most well known. Zombie Massacre followed in 1998, but it is not Gloom 4. In 2017, developer Earok of the Amiga community released the Gloom source code as-is to Github. Due to me being unfamiliar with the legal situation regarding that release, i will not link to it.
However, developer Swizpig has been working on a port of the Gloom source code to Windows and Linux, entitled ZGloom (Yes, i am not making this up.). It is still a work in progress, but there are exes available for Gloom and Zombie Massacre, aswell as the source code. The Gloom Level Editor however does not seem to be ported over yet.
Ofcourse, the Gloom technology is in several ways more limited than Doom's, but a port to modern systems, in a similar fashion as CatacombGL, is an interesting foray.
Screenshots:

Links/Downloads:
ZGloom Github
Interesting trivia:
Developer Nitta and others have made several games on the Gloom Engine for Amiga and Amiga CD32. With ZGloom, there is a possibility that these now can be ported over. These are:
- 8Bit Killer
- Death Mask 3D
- Did It Come From The Desert?
- Ultimate Maze
- X-Men: Mind Games