Sudoku looks like a pastime for a quiet evening, but at the top level it is timed, scored and refereed like any other competitive discipline. Solvers race against a clock to complete number-placement puzzles under exam conditions, and the fastest, most accurate solver wins. The sport is organised worldwide by the World Puzzle Federation (WPF), which runs the annual World Sudoku Championship (WSC) alongside its sister event, the World Puzzle Championship.
Objective
The basic puzzle is unchanged from the newspaper version: fill a 9×9 grid, divided into nine 3×3 boxes, so that every row, column and box contains the digits 1 to 9 exactly once. In competition, the objective shifts from simply finishing to finishing correctly and quickly, since rankings are built on points earned per puzzle and the time taken to solve it.
Rules and regulations
- A championship runs across several rounds, each with a fixed time limit and a set of puzzles worth different point values depending on difficulty.
- Competitors work alone during individual rounds and in groups of two to four during team rounds, where puzzles are often split between members or solved as relay chains, with one answer feeding into the next puzzle.
- Beyond classic sudoku, solvers face dozens of variants with extra constraints, such as diagonals, killer cages or irregular-shaped regions.
- Incomplete or incorrect grids typically score zero for that puzzle, and some rounds apply time penalties for errors.
- Calculators, phones and reference notes are banned, and solving is done entirely by hand with pen or pencil.
- After the qualifying rounds, the leading finishers usually go through to a play-off, often solved on whiteboards in front of the other competitors, to decide the individual champion.
- India has its own national championship, run by Logic Masters India, which feeds solvers into the world event and has previously hosted the WSC.
Equipment and playing area
- The “equipment” is deliberately basic: a printed puzzle booklet, a pen or pencil, and an answer grid to fill in.
- Competitions are held in exam-style halls with rows of desks, supervised by invigilators who enforce timing and collect papers at the end of each round.
- Some events now run selected rounds on computers or tablets rather than paper, though pen-and-paper solving remains the norm at the World Sudoku Championship.
Scoring
- Each puzzle carries a points value set by the organisers, usually higher for harder puzzles, and solvers who finish within the time limit collect those points plus, in some rounds, a small bonus for speed.
- Wrong answers score nothing and can trigger penalties in certain formats.
- Total points across all rounds decide the overall individual and team rankings, with a separate play-off often used to settle the top individual placings.
