Sudoku
How to solve Sudoku
From sole candidates to X-Wings, Swordfish and forcing chains: the techniques that crack hard and extreme puzzles.
Solving guides
Stuck on a hard one? Each guide starts with the rules, then works through the techniques in order, with a worked example for each.
Killer Sudoku
How to solve Killer Sudoku
Cage combinations, the rule of 45 with innies and outies, and cage splitting: the techniques that crack hard Killer Sudoku.
Calcudoku
How to solve Calcudoku
Cage combinations for + − × ÷, the row and column totals rule, and mixed-operation puzzles.
Futoshiki
How to solve Futoshiki
Using the inequality signs: smallest and largest values, ruling out extremes, and chains.
Hashi
How to solve Hashiwokakero
Islands with one neighbour, full islands, blocked bridges and keeping the network connected: the techniques that solve hard Hashi.
Hidoku & Numbrix
How to solve Hidoku and Numbrix
The number between two, counting steps, dead ends and trapped cells: the techniques that solve Hidoku and Numbrix, with diagonals and without.