DWG-300 · Reference shelf
How to play
Short rules for every puzzle on the wall, and longer guides for when the short rules are no longer enough.
Guides
- Sudoku techniques, from singles to wingsA practical tour of the sudoku techniques our levels are built on: hidden singles, single candidates, pointing pairs, pairs and triples, X-Wing, Swordfish and the wings.
- Sum combinations for killer sudoku and kakuroEvery cage or run size from 2 to 9 cells with the sums that allow only one set of digits, plus the rule of 45, the missing-digit trick and crossing runs.
- Line logic: nonograms and binary gridsHow to solve nonograms and binary puzzles one line at a time: overlap, edges, crosses, doubles, sandwiches, balance and the one way to finish a line.
- Counting moves: bridges, skyscrapers and lightsCounting arguments for three puzzles: bridge capacity and isolation in bridges, the cap rule in skyscrapers, and light chasing with bottom-row tables for every lights board.
Rules at a glance
Sudoku
Fill the empty cells with the digits 1 to 9. Every row, every column and each of the nine 3×3 boxes must contain each digit exactly once. The digits printed at the start — the givens — cannot be changed.
Killer Sudoku
Fill the grid with the digits 1 to 9 so that every row, column and 3×3 box contains each digit once, exactly as in ordinary sudoku.
Nonogram
Each number beside a row or above a column is the length of a block of filled cells in that line, in the order given. Blocks are separated by at least one empty cell, so a row clue of 3 1 means a block of three, a gap, then a single filled cell.
Kakuro
Fill every white cell with a digit from 1 to 9. A clue in a dark cell gives the sum of the run of white cells to its right (the upper number) or below it (the lower number).
Binary
Fill every cell with one of two symbols, shown here as a ring (0) and a dot (1).
Bridges
Each circle is an island, and its number says how many bridges end there.
Skyscrapers
Fill an N×N grid with buildings of height 1 to N. Every row and every column holds each height exactly once.
Lights
Tapping a lamp switches it and its direct neighbours above, below, left and right: lit lamps go dark and dark ones light up. Lamps on the edge have fewer neighbours.