Games & Puzzles
Sudoku
Nothing is guessed: every step can be deduced
A pencil and paper, or a free app, at no cost. The key realisation is that guessing is never required: any properly set puzzle can be deduced step by step, and if you are guessing there is a clue you have not spotted. Above that sit named techniques with clear difficulty steps. It fits queues and commutes well.
First stepSolve five easy puzzles in a free app without guessing, and be able to say which clue gave you every number.
Barriers
Cost to start
Free
Going deep → $50–300
Alone or with people
On your own
Effort
Sitting
Without a teacher?
Self-taught
One session takes
Under 30 min
Where
At home
Why people take it up