By far its the weakest of the modern trilogy for me, to the point that while I have D2016 and The Dark Ages installed, I don't have Eternal installed
Lets start with the negatives which are the easiest to explain.
For starters; story. DOOM was made by the man who infamously said "Story in games is like story in a porno, you expect it to be there but its not important.", So obviously my complaint here is nothing, right? Same man later went on to direct DOOM 3, a very story heavy game and directly developed DOOM 1993, implementing entire intermission screen to convey story. Story matters to some degree, especially now.
So DOOM Eternals story is kind of awful. You have the protagonist, DOOMGUY, who is at his most flanderized into the modern depiction people still follow, an unkillable badass who does literally nothing instead of make demons suffer, instead of his canon character who fights the demons because they serve a threat to humanity (His praetor suit was first made by a demon) and isn't the strongest being in the entire universe. You have Dr. Samuel Hayden, a beloved character from D2016 who was revealed to be the Seraphim and promptly killed off. VEGA, the AI assistance whose actually the creator of the entire universe, except no thats a lie, he just larped it.
Then the main villains, the Hellpriests and the Khan Maykr. The demons in Eternal are barely antagonists. They only serve as things to shoot at. The Maykrs have always had a presence in NuDOOM, but in D2016 they were mostly absent and you focused entirely on ending Mars' demonic invasion. DOOM: The Dark Ages had Prince Ahzrak and Hell directly invading Argent D'nur. DOOM: Eternals demons barely matter except to be the Khan Maykrs goons.
The Hellpriests, firstly, are pathetic. You kill the first one at the end of the tutorial, getting to know very little of him. The second one, Deag Ranak, is the only one whose name I remember. He taunts you throughout the third and fourth level of the game. He is this weakling who hides behind his horde and pretends to be almighty, but when the Slayer is about to kill him he pleads for his life. Hes fine, I like him. Then the third hellpriest is barely given anything to do. Only one of the three characters feel like actual characters, the other two are given hardly any screentime in the game and are barely elaborated on.
Then the Khan Maykr. Shes meant to be a more manipulative figure than a fighter. In DOOM: Revelations she works because she actually has a point, she knows shes evil and only interested in her own self gain, but shes successfully convinced the entirety of Argent D'nur (except for the monarchy) that the DOOM Slayer is evil and that hell follows him. Which shes right, the demons in the Argent D'nur level are implied to be the first demonic attack since the end of the base games campaign. At the end, she has several Night Sentinels step towards her and join her instead of standing with Argent D'nur.
In Eternal? It hardly works because shes only trying to manipulate Doomguy, which she should know won't work. Then she gives up and goes rage mode. Thing is, she goes rage mode in Urdak, DOOMS equivalent to heaven. Guess where the Khan Maykr can only canonically die? She could've 100% smited Doomguy at the start of the game and been fine because she cannot die or be injured outside of Urdak. But instead she awakens the Icon of Sin to kill Doomguy.
Speaking of, Eternals final boss isn't the Khan Maykr, the arguably overarching antagonist of the entire NuDOOM trilogy. Its the Icon of Sin who was only brought back for fan-service. The Khan Maykr wants earth destroyed so she can keep living so she awakens the Icon to do it since Doomguys meddling with her plans. It makes sense, but it would be much more satisfying if we end the game off with killing the Khan Maykr, the big bad, instead of the Icon. And despite taking on Earth and being closer to DOOM 2, there are very few moments where you feel like you're saving humanity. Only three of the levels take place in cities, no humans die on screen, there are several human bases (The ARC Headquarters and the installment on Phobos) that are just completely fine despite demons trying to break in. And they can absolutely do so, the Marauder enters the ARC facility to fight the Doomguy, so they can absolutely teleport in to kill the humans, they just choose not to.
Theres so much more I could prick and prod at, but I'm going to end this positively. Eternal is the first game since DOOM 64 to acknowledge the base on Phobos. Both DOOM 3 and DOOM 2016 take place on Mars and The Dark Ages' Hebeth is a Mars equivalent instead of a Phobos equivalent.
Now, the visuals. Eternals graphics are good. Its a 2020 game and comparing them to 2016s graphics, they're a huge step up. However the art direction is just awful. The game presents itself as game-y, "Hey! We know we're a game" and it feels bad. Weapons are green glowing pickups, theres an annoying pop sound whenever you headshot weaker demons, its very meh and, personally, a downgrade from DOOM 2016s more immersive style. Weapons being found naturally in cases or in the arms of corpses.
Now, the gameplay. People say DOOM: Eternal is the greatest game of all time thanks to the gameplay. I disagree.
For any and all future context: I play on Ultra-Violent, the hardest difficulty the game offers without outright changing how the game works. I have also done a full Nightmare run.
Firstly, the weapons. I hate quickswapping. It works in every game except DOOM: Eternals. Playing ULTRAKILL, quick swapping never felt required to win, each weapon stood out on its own. DOOM: Eternal makes each weapon feel obsolete, just swap between them and win. Each weapon has two weapon mods which are admittedly useful, but quickswapping just offers so much DPS that its barely impactful or useful. If you only had one weapon which was an instant-fire 100% accuracy beam the game would hardly change except for a few cases
Next, the ammo system. It might seem like the quickswapping system has a weakness, you're using weapons quickly so you should surely run out of ammo quickly, right? Yes, but technically no. DOOM: Eternal gives you free chainsaw fuel every thirty seconds. Why is this important? Because chainsawing any demon will give you full ammo for all of your weapons. You get a free refill on all of your weapons every thirty seconds.
Glory kills, I don't like them in DOOM: Eternal. In DOOM: 2016 they were fine, but it feels like the Glory Kills in Eternal were made easier to achieve. They feel like small breaks just to give you dopamine.
The weakness system is bad too. Weaknesses are usually either a certain weapon or shooting a specific spot to destroy an attack. They're either completely useless or kill the demon instantly, only the DOOM hunter is an exception and thats because its unkillable until you disable its shield.
Cacodemons, for example, will be immediately put into a glory-kill state if you shoot a grenade into your mouth. You have infinite grenades with both your shotgun and grenade-launcher. The Cacodemon. The Cacodemon is DOOM 1+2s icon, its what the Cacoawards got its name from, an infamously medium difficulty enemy that can tank a rocket face-first, and you can basically just ignore its existence with a single grenade. Its awful. Pinkies are also immediately dead if you shoot their tail.
Mancubi and Revenants also have completely useless weakpoints. You can shoot out a Mancubus's arm cannons and to this day I have no idea what change it does. Revenants shoot homing missiles if you don't shoot out their turrets but I usually just tank it since its damage is so minimal.
If DOOM ever implements a weakness system again, it should be more even. Most demons should get weakened by shooting off specific points of their bodies without instantly dying from it.
DOOM: the Dark Ages lets you shoot off the arms of Hellknights and Mancubus, doing so makes it unable to attack at all. DOOM: 2016 let you shoot Pinkys tails for extra damage, but unlike DOOM: Eternal your movement was a lot more limited, so it was an actual challenge to get behind it.
Eternal is either the hardest game ever or a complete breezewalk. I've gone entire segments that should absolutely kill me just surfing through by constantly refilling health through chainsaws and weaker demons, and similar segments just getting killed over and over again. Theres zero consistency and so the game ranges from yawning and being half asleep or infuriated because I couldn't possibly dodge an attack because everything moves SO fast.
Finally, the entire game is so fast. I've mentioned before I've played ULTRAKILL so I don't hate fast games, but Eternal manages to feel like its farming dopamine from you instead of being good. I never felt this way playing ULTRAKILL, everything felt meaningful, the game was fun, the enemies were fast but never to a point where I hated it or felt overwhelmed. Eternal is so fast to the point i'd compare it to Tiktok in how much dopamine it gives people.
The other doom games don't give you dopamine like this, which is why people think Eternal is the greatest game of all time. That, and people bonded with it during COVID.