Sniper Ghost Warrior 2.

Hunt Showdown

Escape from Tarkov checks all these boxes.

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

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

“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 …

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

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.

Postal 2

I highly recommend Void Bastards

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.

Insurgency Sandstorm

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.

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.

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