I was supposed to write into Quest! Quest! about this but dropped the ball so now it’s a blog post. So first I’ll say that if you enjoy adventure games, you should listen to the very good and funny Quest! Quest! podcast. The topic of co-op adventure games had come up and there’s not a ton, but they exist. This post is also going to ignore the escape room games out there. It seems like there’s a few of them and people like them, but I just know nothing about them because I’m more focused on traditional adventure games. But Escape Academy and Escape Simulator are out there and seem nice. This is also ignoring that really any adventure game can be a co-op game if you just share your screen and work together to solve puzzles.

The We Were Here series has you and a partner split up as you walk through a series of puzzles in a location such as an old castle and communicating through walkie-talkies about what you see. The game wants you to communicate through the in-game chat and not a voice chat outside of the game like Discord because of how walkie-talkies work and only one person being able to talk at a time. The first game in the series is free if you want to try it out.
The Last Night of Alexisgrad is an asymmetric, two-player interactive fiction where each player takes on the role of a leader of a nation on the last night of a war. It’s built in Twine and the way this one works is that you each play up until a certain point, the game provides you with a code, and the other player inputs the code that you received to see where the game takes you next. I wouldn’t say this one is co-op at all, but it was interesting to see a multiplayer Twine game and I really enjoyed the writing in it.
And of course there can’t be an adventure game article by me without mentioning Myst Online. It’s one of my favorites. It’s still up and completely free too!
The rest of these I haven’t played but hope to some day. If you’re reading this and we know each other, let me know if you want to play one of them.

Tick Tock: A Tale for Two is a 2D point-and-click adventure where you are both trapped in a magical world and must escape. It features cross-platform play and the artwork looks nice.
Operation: Tango is a first person 3D adventure where it looks like you and a friend are doing spy stuff to save the world. A nice thing about this one is that it looks like only one player has to buy the game and the other player can play for free.

Whispers in the West is a point-and-click western murder mystery that supports co-op for 2-4 players. The base game includes a tutorial, mini mystery, and full length one with DLC for additional mysteries. This is another one where only one person has to buy the game and everyone else can play for free.
The Past Within (Steam/Itch.io) is a co-op first-person point-and-click adventure in the Rusty Lake series. Puzzles involve one person being in the past and one in the future and communicating in whatever way they want. I haven’t played it but it looks like they aren’t directly connecting to each other over the internet in-game and just rely on what the other person sees to solve puzzles. Both players need a copy of the game to play but it sounds like both paths are very different.

A Lively Haunt is a horror graphic parser game in the style of early Sierra adventures like King’s Quest and Space Quest where you walk around and type your commands. This one supports two players on the same machine by having two keyboards plugged in, but I imagine that playing through something like Parsec would work too? I learned about this one from WilcoWeb!
I suppose all the games like It Takes Two and A Way Out by Hazelight Studios could count as well. They aren’t my thing but good luck to all game developers I guess.
Shivers 2 and Zork: Grand Inquisitor also shipped with multiplayer. I believe they just allowed a player to connect and use a mouse cursor to point at stuff and type comments to help solve puzzles. The online services for both shut down a long time ago but I think it’s interesting they were attempted. I’m guessing they were pressured to insert online multiplayer into their games since they were the hot new thing, and it feels like a proto version of sharing your screen over Discord. The demo for Quest for Glory 5 also shipped with co-op and it would have been interesting if that made it into the full game. My understanding is that you can still play that one but it’s a massive headache to get working.
Well, that’s all I could think of but I would love to hear other recommendations!
Oh that’s such an interesting topic! Thank you for sharing the list!