Pure Domino allows you to play online in three forms: LAN Steam Lobbies Direct connection to the server. While the game will try to open the ports when you host as a server, some routers do not support protocols to do that dynamically. Here are the ports you need to set up in your router if so. Ports to play the game TCP: 25777, 25778 and 25779 UDP 25777 Lan Lobbies UDP: 4446 Multicasting Enabled (usuall...