Technique guides

Sudoku

46 techniques

From naked singles to alternating inference chains — every technique the 9x9 board asks for.

Killer Sudoku

31 techniques

Cage combinations, the rule of 45, and the innie/outie arithmetic that opens a board with no digits on it.

Kakuro

20 techniques

Sum combinations, run intersections, and the arithmetic that narrows a white run to one digit.

Hitori

11 techniques

Shading rules, connectivity traps, and the patterns that force a duplicate to stay.

Bridges

8 techniques

Island counts, forced spans, and the isolation arguments that rule a connection out.

Nurikabe

18 techniques

Island reach, sea connectivity, and the pool rule that decides most cells for you.

Slitherlink

31 techniques

Corner parity, loop reachability, and the edge deductions that grow a single closed loop.

Battleship

12 techniques

Fleet counting, forced extensions, and the diagonal rule that turns a hit into water.

Skyscrapers

21 techniques

Visibility clues, height permutations, and the cross-line consistency that settles a row.

Light Up

9 techniques

Beam blocking, clue crowding, and the cover arguments that place a bulb without guessing.

Futoshiki

20 techniques

Inequality bounds, Latin-square subsets, and the line consistency that pins a row down.