I’m surprised to not see the Sniper Elite games recommended here, if we’re talking single player. They’re definitely a bit formulaic by now, and story/dialogue is not worth paying attention to, but they’re slow, methodical, and a lot of fun!

There’s a bit of a Hitman vibe to the later ones, approaching objectives almost however you’d like, and they can absolutely get hectic if you find yourself in a compromising position.

Escape from Tarkov checks all these boxes.

It’s by my definition dead tho, as its playerbase consists currently of highly experienced players and cheaters.

I play it but I also got close to 3000h.

Edit: It’s the polar opposite of cod, the only thing they have in common are guns.

“Ready or Not” seems not to be recommended yet. It is basically a SWAT simulator you can play single player or together with 4 people.

You can choose your loadout freely to complete the missions. I recommend going blind into the missions on a first playthrough as some have some unexpected surprises …

Hell Let Lose is a WW2 simulator game,

You can play it like cod and run around but all that gets you is killed by some guy who’s creeping a corner or whatever.

It’s best played slow and tactically following orders from your squad leader who gets orders from the match commander.

One or two bullets will kill you and half the time if you’re not being careful you won’t know what happened to you.

Then the slow pace is suddenly juxtaposed by a fierce fire fight defending your location while tanks shell you and artillery rains down.

Escape from Tarkov has a PVE mode now, so you dont gotta deal with the sweaties of PVP. Any of the tactical looter shooters have a slow vibe. Tarkov was intense and difficult for a long time, but my bestie was my Sherpa, so to speak, and we go into maps together and I can handle myself now. It has a hideout building aspect, so your loot goes towards something. There’s quests from the trade vendors, that all builds a lore to the game that has a lot of secrecy. I dunno a lot of it, but it’s fun to figure out. It also has weapon building, where all the weapons are able to be taken apart and sold for parts or pieced together with the parts you want. The ammo has stats on what can penetrate armor, and the armor has a plate system so you can buy or find better plates for it. There’s a durability aspect too, and weapons can jam and need to be evaluated and then clearing the malfunction. There’s bosses, too. And different factions to deal with. Many are ill equiped, and some are decked out in gear with big weapons. Your character can die with one shot if there’s no armor there. Or you can tank a bunch of shots if you’re kitted out. There’s even a flea market that’s player based. So the prices can make your character rich, if you play the market or sell stuff. Like, selling a chocolate bar can net you 100k, because they’re fast food during in-raid. Oh, and there’s a whole water + food system. So you have to find food and water to keep that going. You have to use the right meds for the right situation; splits for fractures, bandages for light bleeds, tournequits for heavy bleeds, pain killers, injector pens for status effects and medkits to heal, after you deal with all those situations. Some medkits even cover a lot of the various things, some inject pens cover various things too.

It’s pretty in-depth.

The game is based in Russia though. Your character is without a faction, despite picking one “USEC” OR “BEAR.” But that’s just how you got into the city; USEC was the corporations mercenary group, BEARs were the military. And it takes place after the fighting, your character sorta got out of the faction. Unless you do a scavenger (scav) run, everyone is unfriendly. Scavs all stick together except the boss and their goons might pop you.

It doesn’t seem to have anything to do with real politics, far as I’ve seen? But the lore deals with the corporate greed, military powers, and regular scavenger people all kinda vying for survival in a war torn city of Tarkov. It’s a weird lore, but interesting for a game and intense gunfights of fire, move, cover, fire, move, cover. Be wary of a clicking grenade and run.

Rainbow Six: Siege

People who play it like COD are the worst players in the game. Everything is designed to reward methodical, team-focused strategy so you can get the upper hand on people who don’t pay attention and try to rush everything.

You might love and hate my answer: Titanfall 2

It’s literally both of these things. Pilots play the extremely fast, twitch-shooting superhuman game while Titans play the slow-paced boots-on-the-ground heavy-weighted gameplay.

It’s the best multiplayer shooter of all time and it survives thanks to the Northstar launcher on PC

Not sure if this is what you’re looking for, but Hunt: Showdown is a pvpve experience set in a fictionalized horror-themed 1900s old west.

The guns have few shots and are very slow to reload. Often your best strategy is to move very slowly and deliberately, looking closely for any movement from other players, taking care not to make any errant noises. Every single sound you make, including right clicking to aim down sights, is audible to your opponent if they’re close enough. One good shot is enough to down someone.

The result is a unique experience that can hit both extremes: agonizingly slow build up of anticipation, or a fast paced chase through the woods to cut off an escape.

Receiver 2, my dude.

An awesomely weird firearm simulation/stealth game, with a storyline consisting of equal parts gun safety, mental health awareness, and cult reprogramming. Almost every function of the player weapon is a different key on the keyboard. Reloading a single magazine is like a 4-6 keystroke sequence. A suddenly jammed weapon is like being presented with a tiny puzzle to solve, while under fire from deadly turret drones. One shot from an enemy kills you. You can and will shoot yourself in the leg. There is fall damage. There is broken glass damage. You are not an action hero, you are a sentient range target. Every bullet matters.

Anyways, it’s very paced, tense as fuck, and a decent challenge. The voice acting and soundtrack are also lovely.

Pretty much any immersive-sim, Prey, Deus Ex, Thief, Dishonored, System Shock Remake.

S.T.A.L.K.E.R Gamma. Completely free if you don’t count the disk space and one of the funnest, and most difficult games I have played.

Running around like most other FPS games will just get you killed. The AI is written in such a way that it correctly understands actual flanking, and when it peeks a corner, it does it exactly the same way a real player would - it’s actually scary.

I snuck into some occupied buidlings and killed every enemy except one. I was in a barn which had a front entrance and a hole blown in the back wall. I knew that the last enemy was out the front, across the road, inside the window of a building there, so I went out the hole in the back of the building and around the side, intending to go behind a fence and then behind their building to get them. When I got to a place I should have been able to see them, they weren’t there. I turned around and they were behind me along the fence - I nearly shit my pants. When I had the idea to go around back, the AI apparently had the idea to run out the front of their building into the front entrance of mine, and take me from behind by complete surprise - essentially the same exact tactic I had thought of.

It was then I realized how great the AI actually was and now every time I play I live in complete fear.

Sniper Ghost Warrior 2.

If you can mind the obnoxious patriotic undertones, Hell Divers is actually my go to game rn. Partly hate it for the mentioned but overall, pretty decent game. I’m not a hard core gamer really (in general) but the game has grown on me and it’s PvE so it’s fun being able to play with others instead of being toxic.

SUPERHOT moves at your pace. Though it definitely does make you feel superhuman, just in a different way.

https://store.steampowered.com/app/393380/Squad/

This is my favourite shooter, based on the Battlefield 2 mod Project Reality. Everything feels, looks, and sounds realistic. Matches take several hours and have a lot of coordination between specialised squads. The maps are huge and detailed. I’ve played rounds where I only fire a couple bullets and like PUBG it’s so much more thrilling than an arcade shooter with nonstop action.