Chucklefish has provided some information on the multiplayer portion of Stardew Valley.
Stardew Valley multiplayer was announced as in the works last year, and it is expected to go into beta on Steam at the end of 2017.
After the multiplayer game is started, handy carpenter and builder Robin will arrive on the farm and put up three cabins. Each of which will house a farmhand controlled by a friend.
Like the player, friends will be able to farm, fight, fish, forage, mine and almost everything else the main player can do, such as take part in festivals. Each will also have their own inventory and when not connected, it can be managed by using the chest in their cabin.
The main player will make the more important decisions, such as when to start or end a festival, when to sleep, and whether to choose to side with the townsfolk or
One of the other fun things mentioned is the ability to marry your friends, which sounds like both a blessing and a curse, depending on the friend obviously. I won't be marrying any of mine, for instance. I rather enjoy being married to my tortured writer of a husband, Elliott. Funny how one's preferences can spill over into video game land.
Putting my silly school-girl daydreaming aside, it does sound as if it could be a fun mechanic, but friends will also be able to marry the available singles in town. In Stardew Valley, the player has to woo their intended, and once they have been wooed sufficiently, the player needs to acquire the Mermaid Pendant. Once the player has done this, it is presented to the NPC.
In the case of multiplayer, if the main player and a friend do decide to get hitched, the Mermaid Pendant won't be used in that instance. Instead, an "alternative method" with similar effort will be required. No word on what that is, just yet.
Chucklefish said the main portion of work on the multiplayer is finished, such as synchronizing multiple games over the Internet. Retrofitting multiplayer into the single-player game was a rather large undertaking as almost "every source file" was touched, and 15,000 lines of code were rewritten.
With that pretty much accomplished, the next stage of development will consist of implementing the farmhand cabins, the events and festivals, multiplayer NPC relationships, UI and menu, and then it's on to polishing, testing and optimizing the multiplayer.
Those who wish to jump into the Stardew Valley multiplayer won't need to set up a server, as friends can be invited onto the player's farm using Steam. For consoles, the invite mechanism is TBD, but will likely be similar.
The beta test is slated for the end of the year on Steam, and when ready for release in early 2018, it will be made available as patch 1.3 patch on Linux, Mac and PC.
At present, local multiplayer, split-screen and PVP are not planned.
Stardew Valley is now available on PC, PS4 and Xbox One. It's expected to arrive on Switch sometime between Q3 and the end of 2017.