GRIS

I know that you said multiplayer, but if I can be one more voice on single player games that you guys may enjoy playing in turns I strongly recommend GRIS. It is so beautiful and I think it suits itself well for shorter play sessions.

What you can do is take turns playing a single player game (if you are in person) such as the last of us. you take turns playing the game until you die etc. Since I assume you are more familiar with games, if it is your turn and you know that something cinematic or cool is going to happen, make sure to die beforehand so they get to experience it.

I mention this/these types of games cuz its a good couch game + you can make a shit ton of popcorn or pizza bites for the person whose currently watching.

Other than that, every recommendation here sounds solid!

From the top of my head I can think two:

• Battle block theater is a platformer puzzle game and really fun to play in local coop, and it runs on almost anything.
• Sonic All stars racing is a really fun Mario kart like racing game with local multiplayer.

Not sure about Linux support though, so check it out first, but both are relatively old titles so I think they have a good chance to run.

If you want some retro, try Dungeon Siege. Works on Linux. I played this game when it came out and recently got back into it because I never finished it there first time. Really chill dungeon rpgish game. Easy mechanics, but I haven't tested how the multiplayer works.

Deep Rock Galactic can be played up to 4 players, but 2 is fine. There's difficulty scaling to what you want to do and you have to want to play high difficulty content to access it. You go around various biomes, mining for resources, fending off enemies. There's a multitude of mission types to play that can be fun to funny.

It was officially released in 2020 but was in early access for longer than that. It'll run well on mid range PC builds and supports Linux though with the typical warning it might be a little janky until you get the right modifications going. The DLC in the game is cosmetics and you have plenty you can earn through regular gameplay.

A racing style game that you two can play around in I believe is called Wreck Fest. It's a demolition styled racing game so crashing, smashing, and bashing are all encouraged. It has from straight racing to demolition derbies with AI.

It released in 2018 and should work fine on a mid-range PC, though might need to turn down some of the physics effects since there's a lot. Its DLC is different cars which isn't really pay to win as they have strengths and weaknesses to them. I've played it on single player and it's still fun, with a friend would be wonderful.

If you'd like a rogue lite kind of game, there's Teenage Mutant Ninja Turtles Splintered Fate. It's a coop rogue lite where you build up power sets and see how they do. Can be up to 4 players but solo is very much viable as well.

Try emulating Kirby and the Forgotten Land using a Switch emulator.

I recommend avoiding people's recommendations for PC-only/indie games altogether. You will be lowering your standards just to get something that 'works' rather than something that's actually worth your time.

Honestly the coop play on Lego PC games is pretty good if you can get over them being cartooney. You have lots to pick from too, so maybe your partner has movies they're a fan of that are represented in Lego games.

Portal 2 has great puzzles for two players, but the timing can be frustrating

I really enjoyed We Were Here with a good friend. It's a coop escape room like puzzle game where you'll play in different rooms but your puzzles interact with the other room and you'll have to communicate and work the two rooms together to solve it

I do not know how well it fits your characteristics but Sea of Stars is a cool retro rpg you can play in coop.

It takes two

split fiction

These two were the top two favs of my wife and I last year. Played it takes two on our steam decks, and split fiction on our PCs. One of them is older and handled it great. Both pcs run linux.

Sonic Racing Crossworlds. The bots are plenty tough on the hardest difficulty. But you can make them easy too.

Semi-casual games that run well on older PCs and linux? Plus no launchers? Let's see.
I got a few but there may be splitscreen ones in this list too. (If that's ok)

• Battleblock Theater
• Biped (maybe?)
• Cassette Beasts
• Castle Crashers
• Children of Morta
• Don't Starve Together
• Dinkum (If Australian Animal Crossing sounds interesting)
• Factorio
• A hat in time
• Guacamelee
• Human Fall Flat
• Hyper Light Drifter
• ibb & obb
• KeyWe
• Kingdom Two Crowns
• Knights and Bikes
• Like, all of the lego games (They're all similar mechanically, so pick one of the newer ones that look good)
• Lovers in a dangerous spacetime
• Magicka (I like the first one but the second one isn't bad)
• Monaco
• Moon Hunters
• Necesse
• Peak
• Resident Evil 5/6 (Yes, really, its a great time in co-op)
• Satisfactory
• Secrets of Grindea
• Split Fiction (This one may be graphically harder to run?)
• Stardew Valley
• Spiritfarer
• Terraria
• Trine games
• Valheim (At least until mistlands)

I'm kind of going off of semi-casual meaning not high intensity shooters or things that require crazy skills. Most of these are pretty easy to pick up and are generally forgiving. They shouldn't have launchers but if they added one in a later update, then dang.

Lovers in a dangerous spacetime was a ton of fun! Very adorable, simple mechanics, plays on one screen, and not too hard. Also came out over 5 years ago so win win

Stardew valley? Farming co op game has a LAN mode so you can play together. You can do a casual playthrough to learn or try to min max like my wife does.

My gf and I enjoyed:

Stardew Valley

Starbound

Cook Serve Delicious 2 and 3

Out of Space

Overcooked 2

Pizza Possum

PEAK

Biped

Cat Quest 2

Cats Love Boxes

Core Keeper

Temtem

These are the good ones (the ones where I felt like she was having a blast) which should run on anything. She’s also not good at games and has a fairly low-powered laptop. Looking back at them I can‘t believe we‘ve played that many lol

We‘re currently playing Schedule I but it‘s so buggy in co-op that I can‘t recommend it…

I’ve posted about this somewhere else too, maybe a different account idk.

But for games to play with people that aren’t really “gamers” I actually prefer single player games with light amounts of fast paced action or none at all. The “coop” comes from taking turns with the controller.

This works well with puzzle or logic games with generous reaction time requirements (again, or none at all), as well as story based games with light action. A lot of these games also come with natural pauses in the story that provide opportunities to either swap who is driving or put the game down for the day.

I’ve had a lot of success playing through many of these titles with partners. I’m sorting these roughly by category and then how strongly I recommend them. Some of these games I haven’t actually played yet, but I know them to fit the overall vibe.

Puzzle/Logic - no reaction time required

• Chants of Sennaar (HIGHLY recommend, requires decent notes and map making, so the person not using the controller still has a job)
• Strange Horticulture (HIGHLY recommend, also requires some light note taking to make life easier)
• Strange Antiquities (sequel to above, have not played yet, high expectations)
• Return of the Obra Din (have not played yet, high expectations)
• The Case of the Golden Idol + DLCs (STRONGLY recommend, got a bit burnt out by the end, but very fun, also light note taking)
• The Rise of the Golden Idol (sequel to above, have not played yet, moderate to high expectations)
• Baba is You (HIGHLY recommend, nice learning curve but becomes brutally difficult towards the end of the game)
• Myst (HUGE game, very good, but daunting and little to no hand holding, detailed notes required)

Kind of a category within a category, haven’t played these, but they’ve been referred to as 1.5 player games.

• Spiritfarer
• Chicory
• Child of Light

Puzzle/Logic - aim and reaction time needed

• Portal 1
• Portal 2 (and its coop if you have 2 devices)
• Portal Reloaded (community mod adding a portal through time with some seriously mind bending puzzles)
• Portal Revolutions (another mod, haven’t played yet but looks fun)
• Viewfinder (HIGHLY recommend, spiritual successor to Portal IMO and a very, very good game)
• Superliminal (HIGHLY recommend, a “Portal-like” that uses perspective as the core mechanic)

Story Based - some action sequences requiring aim and reaction time and some puzzling

• Stray (just a cute good time with some spooky, heart rate spiking moments where you really don’t want your kitty to get hurt)
• Alien Isolation (if you’re horror movie people at all this is like an interactive movie)
• Shadows of a Doubt (might be a miss for a lot of people, immersive detective sim)
• Firewatch (played this a long time ago, might not hold up)
• Dredge (spooky but cute fishing sim with good story)
• Summertime Madness (not much reaction time needed, but still some aim or speed based puzzles)

All of these that I’ve played were on either Arch (custom), Arch (Garuda), or NixOS based systems under Proton. Two of those systems were installed from scratch and they performed flawlessly, so if you’re on a system that handles all the audio and video driver installation for you things should be very smooth. The Garuda machine is a laptop from 2016 that is plugged into my TV and actually saw the most play time for these titles. It held up perfectly. The other two systems were back to back installs on my fairly beefy desktop, but installation and running the games was smooth after the initial effort to get the systems fully functional with drivers and controller support.

I’m in a similar situation with my wife not being particularly interested in games - I’ve had some success in playing LA Noire with her guiding the investigations and interrogations. The jazz soundtrack in particular helped convince her, funnily enough!

Not quite perhaps what you’re looking for, but may work for others with hesitant non-gamer partners.

Kingdom: Two Crowns is great fun in co-op.

Do you like puzzle games? I played Blue Prince with my wife and that was pretty fun. She's not much of a gamer, so I just drove and she took notes. We talked about decisions/speculated on puzzles together.

My wife surprisingly loved Divinity Original Sin 1/2 can be played on controller splitscreen or M/kb

Since you mentioned platformers, Rayman Origins might be worth a look. It's a 2D platformer from 2011 so it doesn't require a lot of power, levels take a few minutes to complete which makes it perfect for short sessions and it has local co-op (up to 4 players).

I tried it recently on my desktop (Pop!_OS, ubuntu based) and Steam Deck, played without issues on both of them.

Civ 6, the whole Picross lineup on the switch (emulated ofc), Cassette Beasts, Minecraft Java (which can be a pain to setup but once its good its good), Halo MCC apparently has a new split screen mod. You get a lot with a switch emulator due to all the fantastic first party games by Nintendo. Also look into Nucleus Coop.

Tl;Dr: try Cassette Beasts

Me and my husband play this on emulator

https://en.wikipedia.org/wiki/X-Men_Legends

Split fiction was great fun for my partner and I, the story is mid but gameplay is probably the best action adventure coop I've played. It has so much variety to offer.

It Takes Two, or Split Fiction, by the same developers. Both are fantastic games, designed around couch co-op.

Abiotic Factor has been a blast with a friend. I don't play a lot of survival games (I prefer more narrative than most offer, and Grounded was a great one for that) and this one doesn't take itself very seriously (you craft weapons and armor from general office supplies a lot of the time... I've never been so excited to find a cache of staplers).

May want to turn the difficulty down if she gets overwhelmed easily, as while they majority of the game is pretty manageable, there are the occasional hard fight.

Something you might want to consider is that often boardgames nowadays have an electronic equivalent. Case in point, my best mate and myself recently played The Dresden Files over Steam.

Portal 2 coop is phenomenal.

Since she likes puzzles, the Trine game series could be nice! I think they added coop multiplayer starting with Trine 2.

If you both like hack 'n slash then Torchlight 2 is also great fun!