No words, no trivia, no luck — just you and the numbers. From gentle warm-ups to grids that demand X-Wing strategies and Swordfish patterns. Every puzzle solvable by pure logic.
Each level demands different solving techniques. Start where you're comfortable, then push yourself up the ladder.
30+ clues to start with. Solved using simple elimination — perfect for beginners or a relaxing mental warm-up during your morning coffee.
Fewer starting clues, more deduction required. You'll need to think about hidden singles and naked pairs. The sweet spot for daily solvers.
Advanced techniques become essential — box-line reduction, pointing pairs, and claiming. Expect to pencil in candidates and think several moves ahead.
X-Wing patterns, Swordfish, and XY-Wing strategies are your weapons here. Each puzzle is a battle of logic that demands patience and precision.
The final boss. Minimal clues, maximum deduction chains. You'll need every technique in the book — and maybe invent a few new ones. Not for the faint of heart.
Numbers not your thing? We have 45,000+ puzzles in every genre imaginable.
A classic sudoku resource with billions of puzzles and clean interfaces. Good benchmark for comparing difficulty calibration across sites.
Master advanced strategies like X-Wing, Swordfish, and XY-Wing with step-by-step visual examples. Essential reading for anyone stuck at the Hard plateau.
Fascinating research into sudoku as a constraint satisfaction problem — how many valid grids exist, minimum clue puzzles, and the logic behind guaranteed solvability.