Prepare to see the most disturbing, sadistic and morbid manifestation of violence that you ever seen in your life. This is the definitive gameplay enhancement mod for the GZDoom and Zandronum engines. Warning: After you see it, it cannot be unseen!
Brutal Doom adds in quite a bit of features and new visuals, essentially being a gameplay overhaul where both you and the opposition deal almost double damage, and everyone gets some new tricks. All the guns are reworked and feel solid to use, and even the Skulltag-exclusive weapons like the Railgun and Grenade Launcher are modified to be in line. Most enemies learn some new moves to get the jump on you, too, but so do you in the way of a kick button and the ability to perform fatalities with the Berserker pack.
Obviously, the selling point of the mod is all the blood. Gibs will fly, the walls will be painted red, humanoid enemies will be helpless and panic when some of their limbs are torn off, and that Chaingunner will be stunned if you kick him in the nuts.
While many claim that Brutal Doom would be Doom if it was made today, it is better described as if it was modernized; obviously, if Doom was created around this time then we would get something very much like the third game in the franchise.
Though I have two complaints about the gameplay. First one being reloads in general - they slow down the gameplay and encourage hiding behind cover. My suggestion would be to remove these off the majority of the weapons, and in turn just slow down the rate of fire or do some other nerf to balance it out. Both the regular shotgun and rocket launcher could do with something like this, but the Assault Rifle is the worst offender.
Second is that bosses like the Cyberdemon are too easy to take out. All you need to do is hit him with seven rockets (yes, seven) to the head and he's gone. Sure, he hits harder, but it's not difficult to avoid a Cyberdemon's attacks.
Apart from all this and that the novelty may wear off a little quick, this gameplay mod is worth looking into. The upcoming Brutal Hexen might be more of the same, but here's to hoping it turns a fairly bad game into something fun.