Stardew Valley’s multiplayer mode is currently in beta on PC

With update 1.3, multiplayer has been added to Stardew Valley, allowing owners of the game to host up to three other players within their game, allowing players to co-operate and develop their homesteads. Sadly full release notes for this beta have not been released, with the update also adding new story elements and items to the game, which includes hats for horses amongst other neat add-ons. 

Update 1.3 is currently in beta, accessible only through the Steam betas tab with the password jumpingjunimos. Those who update to this version of the game should backup their save files (instructions here) as saves from version 1.3 are incompatible with version 1.2, though the movement of save data from version 1.2 to 1.3 is possible. 

Players have the option to open up their farms to others by building cabins on your existing homestead/game save or by starting a new game from the co-op menu (where up to three cabins can be pre-built). Within the game’s co-op menu players can adjust server visibility, making co-op friends only or invite only on Steam. Stardew Valley’s MUltiplayer can also work via LAN, provided you know the host’s IP address.