Welcome to COSUMI! On this site, you can play 5×5 to 19×19 Go (a.k.a. Igo, Baduk, and Weiqi), which is a well-known ancient board game. If you do not know. Play Go Online. Free multiplayer GO game for you to play online! Play against go players from all around the world! players online. ADVERTISEMENT. Play a Person: When you feel ready, try a game online at The Internet Go Server, The KGS Go Server (KGS Tutorial), or any of several other go servers.