Play Queens and learn the techniques
Unlimited boards from 6x6 to 9x9 with one answer each, and a hint that names the technique behind every step.
Play and learn
Puzzles
Boards to play, answers to check and the reasoning behind them. Every puzzle here comes from the same engine as one of my Android games, so each one has an answer you can reach with logic.
Queens
One queen in every row, column and colored region, and no two may touch.
Matchstick
Move one match and turn a wrong equation into a true one.
30 matchstick puzzles with answers
Thirty equations from easy to hard. Move one match to make each one true, then check the explained answer.
Code breaker
Number clues that point to exactly one secret code.
Daily code breaker
Crack a secret code from number clues. Three vaults every day, 3 to 5 digits, one answer each.
Bulls and cows solver
Enter your guesses and their bulls and cows. See every code that still fits and a suggested next guess.
How to solve code breaker puzzles
One method for lock riddles, daily vaults and bulls and cows, with three puzzles solved step by step.
Money challenges
Simple plans for putting a little money aside every week.
52 week savings challenge calculator
Get a dated 52 week chart with running totals for any first amount, then print it or save it as a PDF.
How these puzzles are made
I build logic games for Android, and each game has a solver that checks every board before it ships: exactly one answer, and a way to get there without guessing. The puzzles on these pages run on the same engines in your browser.
That's also where the worked examples come from. When a guide says a cell is ruled out, the solver found that step first, so you can follow it with a pencil and get the same result.