Advanced solving for people who already know the rules: named techniques, deduction patterns, and difficulty ladders for sudoku, logic, and number puzzles. Also useful for publishers who need to grade difficulty honestly.
Queens is a placement puzzle on a square grid of coloured regions. You put exactly one queen in each row, each column, and each region, and no two queens may touch — not even at a corner. This is not chess n-Queens: long diagonals are allowed, and each region still takes exactly one queen. This guide uses a 5×5 board as the worked example.
Criss Cross — also called Kriss Kross — is an intersecting word-fit. Write one letter in each empty white square so each Across or Down clue has its word. Words share a letter where they cross. This guide uses a small board whose first word is CAT.
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A Binary puzzle — the same puzzle you may know as Takuzu, Binairo, or Unruly — is a square grid you fill with two symbols. Each row and each column ends up half-and-half, and no three identical symbols sit in a line. This guide uses a 6×6 board of 0s and 1s as the worked example; the same rules hold when the pair is letters, colours, or pictures.
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