First you need GZDOOM and project brutality, links are down below. ↓
https://zdoom.org/downloads
https://github.com/pa1nki113r/Project_Brutality

Once done you need to make them work with the steam version, I will give a step by step guide on how to make it run and make it count your hours in the game.
1. Unzip all of the contents of GZDOOM into your DOOM folder, replace Dosbox.exe with GZDOOM and rename it dosbox.exe.
2. Once done unzip Project brutality, you can do this with 7zip or winrar but I used 7zip to make it easier.
3. Rename Project_Brutality-master.zip to Project_Brutality-master.pk3 and copy paste it in your DOOM steam folder.
4. Find your GZDOOM folder, for some reason GZDOOM.ini isn't gonna be there when you unzip it, it will however be found by typing in your windows searchbar GZDOOM and you should find the folder with the INI file you need, copy paste it and we will go to the next step.
5. Now once you are here open the GZDOOM.ini file and find the DOOM.autoload. Copypaste Project_Brutality-master.pk3 and you can play Project Brutality and enjoy it like I do.

IMPORTANT NOTICE!
Do not copy it more than once, you can only have one game at the time load with Project Brutality working. Once you are done in the Ini file save and you are good to go, there are step by step guides on youtube too and I am so glad I got it to work, Project Brutality is so much fun.

Enjoy fellow Slayer, RIP AND TEAR UNTIL IT IS DONE!
https://www.youtube.com/watch?v=zahGAByGi54

Weapons are mostly the same as in the original, they do however feel more powerful.

Gore is increased to 1000, there is demon guts flying everywhere from a shotgun blast and gibs all over the place when you use a rocket launcher as an example.

You can aim down your sights, this adds a new level of play to the game since now you can take down enemies from a longer distance.

You can still run and gun but aiming does actually affect your accuracy, it is a nice touch and adds something more to DOOM outside of just your regular power fantasy you will need to think a little when playing.

Grenades: Project Brutality also adds grenades which is gives you more power. You can throw them at a bunch of enemies at the same time, it is a good way to take care of a large group of demons if you are put in a corner or are low on ammo.

An example of how aiming looks like in Project Brutality.

I am a veteran and only play on Ultra Violence, so I play on Brutal for my runs and honestly it is how I recommend people play it, it is much better experience and far more challenging.