Check out Kingdom Two Crowns. Absolutely brilliant

• A Hat in Time
• Trine
• Spiritfarer
• The lego games
• Knights and bikes
• Human fall flat
• Cassette beasts
• Chariot
• Octodad
• Monaco

I don't remember these being particularly violent but maybe are worth a look:

• Pit people
• BattleBlock Theater

I also liked Moon Hunters and Children of Morta but those are harder.

Divinity Original Sin 1 is also good but definitely falls into the violent category. Its kind of goofy too so it could be worth considering. The second game + BG3 are significantly more violent and serious so are harder to recommend with that criteria.

Edit: hmm it seems the formatting is funky in Voyager, should be fixed now

If you're open to doing emulation, there's a multitude of Nintendo games that are amazing couch co-op.

... Genital Jousting.

Me and the wife played a few coop games.

• DERU - The Art of Cooperation is a pretty puzzle game that is satisfying, not too difficult nor does it overstay its welcome.
• We also enjoyed the snake-esque puzzler OmoTomO. Only on itch, not Steam, so you have to install it via the desktop mode. When you're willing to dig a bit itch grants you some shiny gold nuggets for cheap.
• In Lovers in a Dangerous Spacetime you have to run around a spaceship to operate the different parts (engine, guns, shield). More straightforward than it sounds, and the pacing is such that you're not rushed but do get some tense moments.
• Almost forgot Pode which is a very cute 3rd person puzzle adventure game.

Some games recommended by other people in the thread that we can corroborate

• Trine series is good platforming fun with pretty graphics and dialog that is a little on the nose sometimes.
• Kingdom: Two Crowns is good for a few hours at least, can't say I cared about beating it because the levels just keep coming with only minor variations. Definitely a unique blend of tower defense and base building.

Personally I agree on Overcooked, once the novelty wears off it gets a bit frustrating because of the difficulty. Its still fun in groups though.

I’m a fan of taking turns “driving” for slower paced logic or puzzle games. Titles that come to mind:

• Myst
• Curse of the Golden Idol
• Summertime Madness
• Chants of Sennar
• Superliminal
• Viewfinder
• Baba is You

I can highly recommend all of these as they almost universally benefit from more minds working on them together. I would say Baba is the only one that gets REALLY challenging, but there are good mind and logic bending puzzles throughout them all!

EDIT: I’ll also add that Myst, Golden Idol, and Chants of Sennar (Summertime Madness maybe a little) all benefit from solid note taking and map making This provides a great job for the “copilot” while the other person is managing the actual input device.

A way out. Two criminals escaping prison, made by the Same studio as it takes two and split fiction. Full of mini games along the way like the other two and my god the story made me laugh with it's ridiculousness. it's definitely not as good as it takes two or split fiction but well worth a go imo

If you don't want something too serious, you can try

1. Fling to the Finish
2. Keywe.

Both are cute and kind of funny, doesn't get too difficult as long as you don't chase highscores.

Unrailed is less chaotic than overcooked, but can still get a little stressful as tasks pile up.

My wife and I were having fun doing co-op on the Trine games. Coordinating your character switches to cross obstacles can be pretty fun. The Lego Star Wars games were also fun for us both to just mess around and cause chaos.

Spelunky 1 & 2

Monster Prom, Monster Camp, Monster Roadtrip

Also seconding Kingdom: Two Crowns

Keep talking and nobody explodes could be a fun one, only needs 1 device and the other player needs the manual which can be on a phone or printed out. You could even play it over a phone call.

A bunch of retro games have good couch co-op support & the steam deck can emulate pretty much all of them

Zombies ate my neighbors, smash TV, 2-d brawlers like TMNT turtles in time, double dragon, and streets of rage, Goldeneye, toejam and Earl, bubble bobble

Ballers gate 3? Pretty sure that runs on. Steam deck.

Ship of Fools is -60% on steam right now and I can't recommend this game enough. It's a rogue lite where you both need to protect a ship from monsters maning the cannons and it's an absolute blast! It has good progression and it's intense but not in annoying sort of way.

Split Fiction is peak, gonna be hard to beat. Too bad you can't do 'a way out' it's very well done. Might want to look into tweaks for those "unsupported" games, as many of them work fine. Unraveled 2 is a good example.

Otherwise, If this is something that is really becoming your thing, it might be time to hook your PC to the TV or invest in a console. If you go console, you additionally open up the world of games that require individual screens (crossplay games-you on steam deck screen and them on TV screen, but still sitting together OR you on pc and them on TV if same room).

Our couch coop at some points was me with my laptop on a stack of books on the coffee table while she was on a ps4. Played Aragami this way, for one.

They may seem silly, but there are a slew of Lego games that people get really into and are very impressive. Human Fall Flat also has some silliness, but good puzzles at times

Brothers: tale of two sons

Broaden your horizons, start using emulators.

Star Wars: Jedi Power Battles

Kirby and the Forgotten Land

Super Mario Wonder

Any of the Warriors games (just don't buy it, don't reward them for releasing the same damn game 20+ times)

Legend of Mana (highly recommended, please don't sleep on this)

Destroy All Humans 2

Ratchet: Deadlocked

Divinity: Original Sin

Resident Evil 6

Halo: Master Chief Collection

Lego Star Wars

The Tales games are long and go up to 4 players. I'd recommend them if you have more people to join.

Be prepared for a few roadbumps while you acclimate yourself to using emulators. It won't be smooth at first, but it gets easier the more familiar you become with it.

crawl, rounds, ship of fools, pico park (better with a large group), risk of rain returns (2 would also be good except that it doesn't actually support local multiplayer, only online).

Unravel 2 :) It's a beautiful little co-op game with lots of puzzle-y problems to solve and some dynamic ones as well

If you like puzzle games, you might try a game that's not technically multiplayer but that the two of you can work on solving together, which is what my wife and I do. Good candidates for that are Case/Rise of the Golden Idol, Lorelei and the Laser Eyes, and we're currently playing Blue Prince.

https://www.co-optimus.com/system/4/pc.html

We just started the spiritfarer. Absolutely worth it

Lovers in a Dangerous Space Time

Manage your malfunctioning space ship together while fending off waves of enemies.

Very fun.

My gf is pretty new to video games but these are a few she enjoyed

Trine 2/3

Snippets

Castle crashers

Unravelled

Diablo 3

Children of morta - my gf also doesn’t really like pixel art but this turned out to be one of her favourite games

My SO isn't that big of a gamer but these are the games we've played together:

Lovers in a dangerous spacetime Battleblock Theatre Octodad

I don't know how the tolerance for difficulty is for you guys but I think it's worth a look

We enjoyed A Way Out. Gonna try Sea of stars soon.

Death Squared. Puzzle solving, each player controls two blocks on the map used to solve the puzzle.

I'm not even a huge platformer guy, but Rayman Legends is absolute peak and a fantastic, chill co-op game. The music levels in particular - where the already great soundtrack is synced in time to your jumps and hits - are incredibly satisfying and so well made.

I'd also be remiss if I didn't suggest Blue Prince. It's not co-op per se as it'd only be one person at a time "driving", but the game is about puzzle solving so who holds the controller doesn't really matter. It's a fantastic game if you enjoy puzzles and escape rooms. My sister isn't even a gamer at all but I recommended it to her fiancé and they've been playing together and even she's been enjoying it a lot. From my own experience playing it on my own I also think it would be much more fun if playing alongside someone else. I've often missed having someone to bounce ideas off when stuck.

Blur...from archive.org

My partner and I make a point to occasionally play through a couch co-op game as well. Here are some of the things we enjoyed.

Phogs - Currently playing this. It's a cute, dog-themed puzzle game thing, where you play as two heads of a single long dog-thing. We're enjoying it, but we're not particularly deep in, and I do wonder if it'll get Ibb and Obb samey, but it's worth checking out imo.

Cassette Beasts - Couch co-op, Pokemon inspired, adventure RPG with great storytelling, fantastic music and a retro aesthetic. The world is very Zelda-like in exploration and puzzle solving, while combat is Pokemon double battles. Highly recommended, just be aware that one player gets to be the player-made protagonist, while the other is one of an interchangeable series of partner characters.

Sea of Stars - The co-op update did a lot of good for this game. A Chrono Trigger inspired, faux-SNES era, indie RPG. There's a lot of unvoiced dialogue, which I could see as being a barrier to enjoyment as a multiplayer game, but the game is paced quite well, so I don't think it's a huge problem. Also, players do take turns inputting commands, but everyone is responsible for the timed hits/blocks, and you each control a character of equal agency in the overworld, so it avoids the largest co-op turn based RPG folly of having one player and one half-watching "follower." There are a ton of accessibility options/features (difficulty is VERY malleable), and as an added bonus, there's a free story DLC coming on the 20th.

Children of Morta - This is perhaps the most "hardcore" of my list, but the girlfriend, despite explicitly not enjoying "hard" games, really really enjoyed this one. An action-RPG with some very light roguelike elements, Children of Morta has you play as a family of hunter-gatherer-warrior types in a fantasy world, working together to stop a malevolent power from corrupting the physical world. Each family member has a different playstyle, their own skill tree, and a lot of personality. The game is very story driven, with a few moments being taken between each run for the fantastic narration to drip feed the narrative, slowly teaching you more about the world, the characters, and their family dynamic.

These are the ones that came to the top of my mind, either because they were particularly good or, in the case of Phogs, is ongoing. If I see anything else worth mentioning when I look at my Steam list next, I'll add.

Cult of the Lamb maybe?