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. Sign In · Games · Leaderboards · Chat · Learn to play Go · Puzzles · Tournaments · Ladders · Groups · Forums · About · Other Go Resources · Support OGS. Play · Sign In · Chat · Puzzles. Welcome to Go! We'll be learning on a 9x9 board (or “goban”) today. As you get better at the game, you'll play on 13x13 and 19x19 boards as well. Go is a two.