The latest game from Milkstone Studios, Farm Together [Steam], is now in Early Access along with same-day Linux support and it's actually really sweet.
Disclosure: Key provided by the developer to our Steam Curator.
It has a nice day and night cycle along with different seasons, a customizable avatar and tractor with lots to plant and grow. There's animals too, but of course it's the sweet kind like eggs and milk—not burgers. At least, that's what it seems like so far, we have yet to harvest our pigs to see (update: yup, no violence, pigs seem to give truffles). There's a level up system, which does take a little time to get through which allows you to unlock various new crops, animals, decorations and so on.
It's very much a sandbox experience, there's no story and a basic tutorial to get you going. I like that though, it allows you to just do whatever you want, which makes it a vastly different experience to Stardew Valley.
The developers say they plan to add content on a weekly basis, so it's likely one we will keep checking on. What they have already is impressive though and works really nicely on Linux. I've only noticed two bugs so far, one is where input was doubled up when I entered my farm name, the other is where the farm level doesn't quite sync up all the time between different screens. Apart from that, it's super smooth on the highest settings.
What's nice about the game, is that it has a permissions system that will allow friends and strangers from across Steam to join in. You can set different permissions between friends and strangers too, so if you want friends to help build, but strangers to only be able to help harvest you can do that.
I can also confirm cross-platform multiplayer works perfectly between Windows and Linux.
For those of you who like your more casual and chilled out experiences, this is a game I'm going to easily recommend already. Looking forward to watching this title grow.