Modder ‘swc132994’ has released an unofficial update to Sergeant_Mark_IV’s Brutal Doom 64 v2. Brutal Doom 64 Version 2.5 contains many bug fixes as well as added monsters from Onox792’s Project Nightmare among other additions.
Going into more details, version 2.5 adds new optional nightmare monster spawner and performance option. It also new player classes, as well as new difficulty modes. Not only that, but it revamps Classical mode by removing stamina and adding back the vanilla Doom 64 chainsaw.
Brutal Doom 64 V2.5 adds new gibs for the spectre, nightmare imp, nightmare spectre, nightmare cacodemon and hellhound. Furthermore, the detached limbs are the same colour as the killed monster.
You can download Brutal Doom 64 Version 2.5 from here. Below you can also find some videos from it.