A player then may join the server from the game menu by choosing the Multiplayer option.
The server runs on port 7777 by default, and it must be port-forwarded in order for other players be able to join. If one can't portforward, one may choose to use a VPN service like Hamachi or Tunngle instead (although in those cases, every player needs to install the VPN software). The default max players is 8, but this can be changed during server start-up, as well as within the server configuration file (serverconfig.txt)