Thank you very much. But I noticed a strange bug (?). While playing I often get to hear a sound that reminds me of an electric guitar. I used the map "Duality" as singleplayer with a lot of monsters and a physics file with overpowered weapons. With normal physics, this sound is less frequent. EDIT: I solved the problem by commenting out the line p:play\_sound(139) in brutal\_marathon.lua.
The main thing to know about this plugin is that if you're going to refer to it, you must use ALL CAPS.
Along with that, you should know that it adds extra gore to every monster that dies. Some monsters spill blood when you shoot them. Bullets/explosions leave marks on the ground and walls. All changes are purely visual. The amount of gore you see is configurable (see readme for details).
This is compatible with M2 and Infinity, and any other scenario that largely uses unmodified versions of those monsters.