Devil's Sudoku: Expert Logic

Most Sudoku apps grade a puzzle by how many cells are blank. That tells you nothing about how hard it is to solve. Devil's Sudoku grades every puzzle by the hardest technique it needs: from pairs and pointing, through X-Wing and XY-Wing, to alternating chains and forcing chains. The rating comes from the Sukaku Explainer, an open-source solver built to rate hard puzzles, so a circle means what it says. DESCEND FIVE CIRCLES Five rated circles, Sharp to Infernal, plus an unrated Warm-up, 1,000 puzzles each. Each circle opens with wins in the one before: 20 in Sharp open Fiendish, and every circle deeper asks for more. The map shows how far into each circle you are and how close the next one is. FOUR WAYS TO PLAY Rated gives you three lives and counts toward your rating. Precision gives you one life, no undo and no check, and counts more. Practice is unlimited and never counts. The Daily is the same puzzle for everyone that day, with one attempt and a streak you can protect. HINTS THAT TEACH Stuck? A hint tells you a move exists, then which technique, then draws the pattern on the board. Those three steps never touch your rating. Only the digit does, and the solve is marked as assisted. LEARN FROM REAL POSITIONS 22 techniques to learn. Each lesson shows a real position from a real puzzle, in three steps. YOUR STATS Your rating over time, your wins, your last games, your speed in each circle and the techniques you have proven. BUILT FOR THE BOARD Corner and centre notes, colour marks, fill all notes, undo, a digit-first mode, a left-handed pad, large notes, and five themes from near-black to warm paper, with a high-contrast one. Lives are rules, never a setting: turning off wrong-digit highlighting does not change them. PRIVATE AND OFFLINE No account. Your game lives on your device and works without a connection. FREE, FAIRLY Free with a banner ad and optional videos you can watch to continue after your last life, earn hints or rescue a streak. One purchase, Devil's Sudoku Pro, removes ads, opens every earlier month of the Daily Challenge and makes those extras instant. No subscription. If you want more hints than play and videos give you, the Hint shop has packs. Questions: [email protected]

Welcome to Devil's Sudoku! • Five circles, Sharp to Infernal, 1,000 puzzles each, graded by the technique they need • Win your way down: each circle opens with wins in the one before • A Daily Challenge with a streak and freezes • Hints that name the technique and draw the pattern before the digit • 22 lessons from real puzzles • Your stats: rating chart, last games, speed and techniques