Brain Nine

Brain Nine is a clean, minimalist Sudoku for iOS, built to play anytime — online or off. FOUR DIFFICULTY LEVELS From Easy to Expert, every board is generated instantly and guarantees a unique solution. NOTES & AUTO-FILL Pencil in candidates by hand, or auto-fill every empty cell with a single tap. SMART HINTS 3 hints per game, always prioritizing the most instructive move. You can also turn on unique-candidate highlighting to sharpen your technique without spending a hint. UNLIMITED UNDO Step back as many times as you like while solving a board. TIMED MODE Turn it on for an extra challenge: every mistake adds a 30-second penalty, and you can pause anytime — the board hides itself while paused. STATS & STREAKS Best time, adjusted time, perfect games, and your current daily streak. LOCAL LEADERBOARD Compare your best times per difficulty, all stored right on your own device. THEME & ACCESSIBILITY Light, dark, or system theme, plus a palette designed specifically for color blindness. ENGLISH & SPANISH The app automatically adapts to your device's language. PLAY OFFLINE The game works entirely without an internet connection. No account or sign-in required to play. Brain Nine includes ads that help keep the app free.