One More Stone

Play Go and review your games with KataGo in a simple, intuitive interface. One More Stone is available on iPhone, iPad, and Mac, with no ads and no subscription.

PLAY AT YOUR LEVEL Play against a computer with calibrated difficulty, or play with a friend on the same device. Choose a 9×9 board for a shorter game, or settle into 13×13 or full-size 19×19. Japanese and Chinese scoring are supported, with adjustable handicap and komi.

PRACTICE WITH HELP Practice mode gives you room to experiment, with undo and redo available throughout the game. When you want help with a position, hints show KataGo’s top three moves. Territory estimates let you see where each player is likely to make points.

FIND THE MOVES WORTH REVIEWING The move-quality timeline helps you find mistakes worth a closer look. Compare your moves with KataGo’s suggested alternatives and see estimates of points lost. For games played in One More Stone, you can explore different continuations without changing the saved game.

KEEP YOUR GAMES TOGETHER Your games are saved and synced through iCloud, so you can start a game on your iPhone and continue on your Mac, or the other way around. You can review your saved games on any of your devices, or export them as SGF to use in other Go programs. Import SGF files to review games played elsewhere.

SEE HOW YOUR PLAY EVOLVES See your win rate against the computer at each rank and how your move quality changes over time. Statistics track strong moves and the frequency of mistakes. Practice games are excluded by default, but you can include them if you prefer.

PLAY AND ANALYZE OFFLINE You don’t need an internet connection to play against KataGo or use the review tools. Your saved games remain available offline, too. iCloud sync requires a connection.