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.
A Codeword — also called a cipher crossword — is a crossword with no clues at all. Every white square holds a number from 1 to 26, the same number always stands for the same letter, and a few letters are printed to start you off. This guide covers the rules, the key strip under the board, and a worked example of cracking your first number.
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A Number Fill — also called a number fit or number fill-in — is a crossword-style grid with no clues and no words. You get an empty grid, the full list of numbers sorted by length, and a few starter digits already printed; fit every number into the grid so the across and down entries agree where they cross. This guide covers the rules, where to start, and a worked example from the starter digits.
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A Word Fill — also called a fill-in, criss-cross or word fit puzzle — is a crossword with no clues. You get the empty grid and the complete list of words, grouped by length, and your job is to fit every word into the grid so that all the across and down entries interlock. This guide covers the rules, where to start, and a worked example from the starter word.
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A Latin Square puzzle is a square grid: each symbol appears once in every row and once in every column. There are no boxes. This guide walks a 3×3, then the same two checks on a 5×5. Sudoku adds boxes on top of this rule. Word Squares is a different puzzle: a letter Latin square with one highlighted word.
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Akari — also called Light Up — is a logic puzzle on a grid of white cells and black walls. You place lamps on white cells so every white cell is lit. A lamp shines along its row and its column until a wall stops it. Two lamps must not see each other. A numbered wall needs exactly that many lamps in the cells that share an edge with it.
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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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The pleasure of a Honeycomb is the overlap — finish one ring of six letters and you have handed yourself a free letter in three neighbouring words. It is a crossword built on hexagons: each numbered hex has a clue, and its six-letter answer goes in the six cells around it. Here are the rules, a solving routine, and a board to try.
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A Letter Wheel gives you a handful of letters with one of them in the middle, and asks you to write down every word you can make that uses the middle letter. This guide covers the goal, the rules that decide whether a word counts, a starting routine that finds words faster than staring at the circle, and where to try one in your browser.
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