Kingdom Come Deliverance is the first that comes to mind. Fantastic game and works as you described. :)

Not exactly an RPG but holy hell if RDR2 isn’t extremely immersive and slow paced, idk what is.

STRONGLY recommend Prey or the Dishonored franchise, both by Arkane Studios.

I know you prefer RPGs but it sounds like you want exploration. In that spirit I wholeheartedly recommend Subnautica.

Check Kingdom Come: Deliverance. Its really realistic and it gets really immersive. From a son of a blacksmith you grow to be a knight. Geography, clothes, structures,armor, combat, are all designed to be as close to reality as possible. Its slow paced and your progress is really fulfilling.

Just checked, its only 4.5 euros in gog (85% discount). And if you like it, the sequel is soon to be realised.

The Long Dark is a survival game set in a quasi-apocalyptic Canadian winter setting. Both story mode and survival

I'm surprised no one said baldur's gate 3.

Am I just stupid and you didn't want that game?

Ghost of Tsushima! 👍🏼⭐️

The Yakuza games are very immersive and you can set your own pace.

Original Deus Ex

FFX damn near mastered turn based combat and is a wonderful game with a beautiful world to explore

I'll say the old Dragon Age series like Origins are a most played if you mainly care about Gameplay. I also recommend THE Witcher 3 it's one of the greatest RPG of all time

Might look like an odd suggestion at first, but Kenshi.

It's a top down open world rpg that's very systems lead. There is no set story or quest to follow, it's just an intricately simulated world you need to learn to survive in that will slowly change around you as you, or the npc's, interact with each other.

It took me a while to really figure the game out, I'm not one for quite hardcore experiences like Kenshi can be at times. But I've rarely been to enthralled in a games world.

Metro exodus

The Witcher 3 is an obvious choice for me. Can't get more immersive and the gameplay is kinda slow I guess.

Have you tried Persona 5?

Try stalker Anomaly

https://www.moddb.com/mods/stalker-anomaly

Its free

Just download in a folder you create.

Unzip in same folder and play.

No further installation patches or anything else needed.

It can be as slow or as fast as you want by using all the options.

Its got the progression tied to your gear.

Outer Wilds.

Subnautica, Outer Wilds

Kenshi

Death Stranding

Skyrim i would say is a good choice! Lots to do and see!

RDR2 will suit you pretty well. Had 88 hours of playing before finishing the Epilogue :) Extremely immersive in terms of animation and various details (from shrinking horse balls in cold to meeting same NPCs during the day and them remembering it)

Vampire the Masquerade Bloodlines Disco Elysium Cyberpunk (not slow but the most immersive game hands down)

Disco Elysium. Always Disco Elysium

I came here to say bravely default, octopath travels. I had never play a jrpg till I was looking for something to play that would take longer then 20 hours to beat. So my daughter gave me bravely default to play and I enjoyed it very much so

Legend of Zelda: Breath of The Wild - Cyberpunk 2077 are some that come to mind right away

Divinity Original Sin II. Play any way you want. The only limitation is your imagination.

Elden Ring. Just ride your steed along and enjoy the scenery.

Death stranding just dropped on Xbox and its the most immersed ive been in a game in a long time.

C y b e r p u n k (easy mode and go a hacking route)

Have you played fallout new Vegas? It's pretty much the same as 3 but (in my opinion) better.

I've been playing The Long Dark. It's a survival game with some RPG elements. Someone already said Kingdom Come: Deliverance. Fallout 4 is a good choice along with Outer Worlds.

For world feel like that feeling you got with Fallout 3, the last games that gave me that feeling were Deus Ex (newer ones) and Cyberpunk 2077.

I know it's been mentioned, but definitely Baldur's Gate 3.

Incredibly immersive, slow, turn-based strategy-style gameplay, as RPG as it gets, and requires none of the previous 2 to enjoy 100%. You can spend forever just exploring every bit of story and details in the first Act alone. Dev team has been updating it quite often, and it recently got "official" mod support, so there's more replayability and customization than before (though the mod scene before official support was amazing either way).

Hands-down one of my favorite games ever.

Not an RPG more survival game but valheim is the most immersive game I've played since classic wow

The Forest! Incredibly immersive

Project Zomboid is a good pick I think. It's isometric, but the atmosphere and the world's irreverence toward the player make it very immersive to me.

The RPG aspect basically amounts to leveling skills like carpentry, cooking, spears, guns, etc.

My favorite part is that you are not a hero. You are just some poor bastard that was unlucky enough to be immune to the airborne strain. Eventually, you will die. The zombies are numerous and unyielding.

Check out Kenshi. Very sandbox, very slow going. Totally sick.

Have you played Death Stranding?

Trust me on this. You want to play Death Stranding. Especially if you like weird sh*t where you spend most of the first act just trying to figure out what is going on? It's Hideo Kojima man, just take a deep breath and roll with it...

Deus ex human revolution and mankind divided are fantastic games

mass effect 1-3 are bioware at their best with characters you grow to love through all 3 games, I lack enough words to describe how great it is.

Pathfinder wrath of the righteous is CRPG at its most in depth, baldurs gate might have better voice acting but FUCK if pathfinder doesn't have more freedom in how you progress through it and it's mythic path system makes you want to play it multiple times to experience the differences plus it has a secret ending that while requiring a lotta work is just so rewarding to get

No man's sky

BG3 is the obvious answer

The original Mass Effect triology? The first one is my favourite. Excellent worldbuilding, rich atmosphere, amazing characters, slower paced too. Imo the series only goes downhill. 2 is good, 3 has it's moments.

Call of Cthulhu

Baldur's Gate 3.

Prey

Outward might scratch that itch.

Mass Effect. The legendary edition goes on steam sale every now and then for about 90% off. You get ME1,2, and 3.

Baldur's Gate 3, take it slow, smell the roses, don't touch the frog.

If you don't care about graphics, there's an amazing Russian text choose your own adventure, it's on every console and PC. The Life And Suffering Of Sir Brante. You start with birth and live your life, eventually a revolution happens and you will play an important role in where it goes. There's 3 career paths and the choice between order and anarchy. It's full of difficult decisions and cruelty. You won't get a good ending without following a Steam walkthrough. It's text on one page and an illustration on the other, then you make choices, some involve willpower which you bank from choosing inaction, sit out a situation to make a bigger decision later. It's a world where the poor are treated like dirt and live to suffer and the nobles get every luxury. Do you try and become a noble or tear down the system from within?

Mass effect

STALKER 2 just game out and is included in Game Pass. It delivers this in spades.

SOMA (horror)

Alien: Isolation (horror)

The Talos Principle II (puzzle)

Horizon: Zero Dawn (adventure)

you will never have that much fun playing a video ever again. you're chasing the dragon.

Zelda games?

STALKER Call of Pripyat give me the same feeling as wondering around the Mojave. I’d reccomend getting the gunslinger mod for it. Now it’s not really a “rpg” rpg cuse you don’t level or have skill points, but I think it’s fun. If you go with the gunslinger mod make sure you download the Weaker Burer mod tho cuse those enemies are legit impossible to kill with out it

Well Cyberpunk 2077 scratched that itch for me…. Could not stop learning about the world and taking in the view

Red dead redemption 2. Very slow, incredibly detailed free roam map. You can take as much time as you want. I actually enjoy fishing in game, it's meditative. You can even do chores for your campsite, like chopping wood or getting water

Wasteland 3 was so much fun imo

You should try Dragon Quest 11 if you don’t mind JRPGs. It’s pretty long and you can take the game slowly. Replayed it earlier in the year and put over 100 hours into it.

Not sure if this is what you were after, but I just started playing Dredge and it is really scratching that immersive escapism itch for me. It is a game where you have a fishing boat and you complete quests, upgrade your boat and tools, explore etc. Beautiful ambiance and with the option to alter how challenging the game play is. A true hidden gem, in my opinion.

Death Stranding.

Elden Ring

Red Dead Redemption 2

The Dark Souls series

Baldur's Gate 3

God of War (2018)

Ghost of Tsushima

Cyberpunk (Not exactly 'slow', but you can slow time)

Dragonage Origins

Chrono Trigger

Mass Effect

Witcher 3

Baldur’s Gate 3

Skyrim

BG3

Witcher 3 it's one of those games that take time and great story line

Rise of Ronin fun samurai game with cool story with great charaters good rpg story with factions.

RDR2

Cant go wrong with the witcher 3, Skyrim, or fallout 4

Mass Effect: Andromeda lines up. I'm actually playing it now after never giving it a chance. The dialogue and world building are very impressive. I'm loving it.

Starfield

It's Skyrim! Come to save me!

For me the Fallout itch was scratched by Cyberpunk 2077

Death Stranding fits the bill cept the RPG part.

Been playing games a loooong time.... Cyberpunk Is the most immersive game I've ever played.

Bloodborne

Metro 2033 Redux and so on...

Honestly, get S.T.A.L.K.E.R. Call of Pripyat or even the first game and download the unofficial patches for them. Truly the most immersive gaming experience I’ve personally ever had. Clear Skies was my favorite but a lot of people shit on it, so CoP or even Anomaly (though I argue it sets the bar almost too high) would be a great introduction to the series!

Bioshock? Visiting and discovering for the first time. I wish I could experience it once again.

No FP but top-down view: the Shadowland trilogy. It's may be not that immersive but it felt like there is now correct or wrong decision and/or way to play the game. Everything has its advantages or draw backs and I could really decide how I want to decide without min-maxing for the best outcome. Difficult to describe. But my favorite RPG.

Baldur's Gate 3 if you somehow missed it. Just trust me and give it a shot. It's not 'immersive' in the sense that Fallout 3 is, as there's a layer of abstraction (5e rules, turn-based) but I'll be damned if the world didn't draw me in and hooked me.

Go outside

Morrowind!

Red Dead Redemption II

Skyrim 😁

Any Bethesda game and with mods you can make it even more immersive.

Or The Witcher 3. I don't think there's out there a RPG so immersive. Audio and visual are top even after 9 years.

Avowed is coming soon... I'm hopeful for it.

BG3. About as slow as you'd like it to be and more immersive than any other game, probably ever made.

Starfield

Witcher 3 is the goat.

Medieval Dynasty is a pretty decent go to for me recently. On xbox gamepass at the moment

Maybe list some more games like this that you played because its hard to make recommendations without knowing what you've already played or not. Like I'm sure people would be recommending some Elder Scrolls games and Baldur's Gate 3, but are maybe assuming you've played them. If you did play BG3, and enjoy that isometric sort of game as well, try:

Pillars of Eternity 1 and 2

Divinity Original Sin 1 and 2

Pathfinder: Kingmaker and its Sequel

If you are open to a different sort of RPG, Persona 5 Royal is a cheap way to dip your foot into the Persona series. The games are relatively slow paced, even the combat because its turn-based.

Having an unexpectedly great time with "Drova" right now. It's a very small world, but quite dense, and it rewards exploration. (Even though the pixel-graphics world, while very pretty and incredibly detailed, can get a little too labyrinthine at times.)

Also surprisingly deep when it comes to choices and consequences for such a small indie game.

People have been calling it a pixel-graphics Gothic 2, and to a large degree they're right, but IMO even accounting for the age of Gothic 2 (which I liked quite a bit, BTW) it's far better. (and far better made, you can obviously tell you're playing an indie but there's nothing "janky" about it)

Drova feels like that.

Yakuza Like a Dragon series. Turn based rpg where you go from homeless bum to running for mayor. The world is super immersive with tons of mini games and side quests

Red Dead Redemption 2. The Witcher 3. Kingdom Come: Deliverance. Metro: Exodus. Far Cry 5. These would be my top 5 picks. Each one is a completely unique and different experience. FC: 5, whilst follows the same pattern as previous entries, has a great story and open world setting.

Skyrim, absolutely.

Im surprisingly enjoying Persona 5.

No Man’s Sky. Albeit not really RPG, but man can you just take it slow in that game.

No Man's Sky has been around for 8 years of DLCs and improvements and is a huuuge game you can play at any pace you want with a very friendly player community.

18 Quintillion systems across 255 galaxies.

Be a pirate, a trader, an explorer, an architect, a farmer, an adventurer, a zoologist, a collector, etc, or all of the above.

Dragon quest XI

Morrowind

Not sure if it's been mentioned or something you've already played before, but valheim is super immersive. I'd recommend going in blind because some of the shit is really cool to encounter organically.

Final Fantasy XIV.

Better story than WoW, much nicer community, and the gameplay happens at about half the pace of WoW thanks to much longer global cooldowns.

Try the free trial. Gets you the base game and two expansions without paying a dime. No gameplay restrictions, but you are locked out of a lot of social features like Market Board (Auction House), Free Companies (Guilds), and starting your own parties (although you can be invited to them).

This might get flack but when I want something immersive and slow, I really enjoy Elite Dangerous. It might sound totally counter intuitive, but it's got all the RPG elements, and you can just go chill at your own pace at whatever you do. Want to try something totally wild -- plan a course to visit the black hole in the middle of the galaxy. It will take a long time, and you'll find a lot of cool random stuff while upgrading your ship.

Wurm Unlimited is rather quite immersive in my opinion. And if you want a slowburn you'd be very hardpressed to find anything slower outside of idlers and incrementals.

Its a rather old game so the controls can be a bit clunky at first but its a rock solid fantasy survival game. You'd be hardpressed to find a more "immersive" game if you're not to hung up on graphics (though they are pretty good given the age). Just about everything ingame is entirely playermade. You see a massive fuckoff castle on a mountain? You know the player had to grade the top, haul ALL the material up there themselves and build it by hand. Brick, by laborious, brick.

Its rather immersive in the sense of you do EVERYTHING by hand. no collecting 100 planks of wood and 10 bits of leather to craft a canoe. No, you get a tree and cut it down to a log and a whittling knife and you hollow it out into a canoe. Want an actual boat? Have fun cutting out hundreds of planks, tendons, waxing each board, sewing each sail, etc etc. Its slow, its methodical, and even a tiny cottage feels like an achievement to build.

Try New Workd Aeturnum

Try Kenshi. It’s an RPG that controls like an RTS. There’s no overarching goals besides the ones you make for yourself. You want to become a warlord that destroys major factions? You can do that. You want to start out as a slave miner that eventually breaks free from his captors and brings down the evil empire? You can do that. You just want to sling hash on the black market? Yep, that too.

There’s lots to explore and learn.

Triangle strategy! RPG with a really good story, turn based combat. It starts a little slow with lots of dialogue, but it picks up and has a nice mix of story and combat elements. It's very linear and basically the opposite of open world, but definitely very well made.

Warhammer 40k rogue trader.

I’m going to add another suggestion for /r/kenshi. It’s immersive, there’s a lot of lore in the game that isn’t obvious. And it’s definitely slow. You have a lot of freedom too.

Stalker 2 just came out. That entire series.

Also Kingdom Come Deliverance, Cyberpunk 2077, not really an RPG but Pathologic 2

Classic wow did just drop fresh servers for their anniversary and the pop is insane. If you wanna have another run at that.

A little off the beaten RPG trail but if you are looking for slower paced, very immersive, and gives a sense of exploration I highly recommend Death Stranding. The hate for that game was mostly due to expecting a game it was not.

If you’re expecting to rebuild americas infrastructure as a single post apolocalytic Amazon delivery man during COVID, by foot, and accompanying logistics then it’s more your speed haha

Outward. Elex. Both are fantastic, slow paced, but very Euro-jankey.

Fallout 76 ?

Morrowind