Sudoku: Play Sudoku

Sudoku, with a coach that explains every move. Most sudoku apps give you a grid and a hint button that fills in a square. This one tells you why: which technique applies, where it is on the board, and how the argument actually works. Then it gets out of the way and lets you find the next one yourself. ELEVEN DIFFICULTIES, PROPERLY GRADED From Very Easy to Beyond Hell. Difficulty is not guessed from how empty the grid looks — every puzzle is solved by the same ladder of techniques a person would use, and graded by what it genuinely requires. Most apps stop at roughly what a newspaper calls hard. That is the fourth tier here. HINTS THAT TEACH Hints arrive in stages. First the region worth looking at. Then the name of the technique. Then the whole explanation, drawn on the board: the cells that form the pattern, the candidates it rules out, and why it holds. Stop as soon as you have seen enough — most of the time that is stage one. A REAL COURSE Fifty-three lessons across eight chapters, from the rules and candidate notation up to forcing chains. Techniques are taught as families rather than as a bag of tricks. X-Wing, Swordfish and Jellyfish are one idea at three sizes. Skyscraper, Two-String-Kite and Crane are one pattern in three arrangements. Learn the idea once and you recognise all of them. DRILLS THAT ARE ACTUALLY DRILLS Practice any of forty techniques on a board where that technique is genuinely the next move, not a random puzzle with a label attached. Every drill is verified: the position really does contain the pattern it claims. SOLVE A PUZZLE FROM A PHOTO Point the camera at a printed grid. The app reads it, checks that it has exactly one solution, and marks any digit it was unsure about so you can fix it in a tap. Then it will walk you through it. BUILT FOR THE LONG RUN Four themes in light and dark. Left-handed layout. Cell-first or digit-first input. Hint highlighting that uses distinct shapes as well as colour, so it reads without relying on colour vision. VoiceOver labels on every cell. Haptics tuned so a completed box feels different from a placed digit. Streaks, records for every difficulty, Game Center achievements and leaderboards, and a heatmap of how well you know each technique. Everything syncs across your devices with iCloud, and works offline. WHAT IS FREE Unlimited puzzles at all eleven difficulties. The daily puzzle. Streaks. Every achievement and leaderboard. Three hints per puzzle. Importing puzzles. The rules, the notation and the basic techniques. No ads, no timers, no lives, no energy meters. WHAT THE FULL APP ADDS Unlimited hints with the complete explanation, the rest of the course, every drill, unlimited camera scanning, full statistics, and every theme. A one-time purchase, or a yearly plan if you would rather pay less up front. Ask Siri to start a puzzle, check your streak, or explain how an X-Wing works. For Terms of Use see: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/