STRATEGY · GUIDES · TECHNIQUES
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Short guides on how to think about number puzzles. Beginner techniques, common mistakes, and the bits people don't tell you. Written for solvers, not crawlers.
STRATEGY FOR BEGINNERS
Sudoku: strategy for beginners →
The four techniques that solve 90% of beginner puzzles. No x-wings yet.
Killer Sudoku strategy for beginners →
Forced cage combinations do the heavy lifting. The 45-rule handles what they can't.
Kakuro strategy for beginners →
Forced combinations do most of the work. The rest is intersection.
Calcudoku strategy for beginners →
Most cages have a handful of valid digit sets. Enumerate, cross-reference, repeat.
Hitori strategy for beginners →
Shade the forced duplicates. Each shade triggers the next — it cascades quickly.
Takuzu / Binairo strategy for beginners →
Two digits, three rules — and they force each other more aggressively than you'd expect.
Skyscraper strategy for beginners →
Place the tallest building first using clue-1 and clue-N, then cascade inward.
Shikaku strategy for beginners →
Factor each clue, place forced rectangles first, use walls to narrow the rest.
Inequality / Futoshiki strategy for beginners →
Count arrows per cell to set min/max bounds — forced cells appear immediately.
Countdown strategy for beginners →
Scan large × small products first, check round-number proximity, fine-tune.
Sumplete strategy for beginners →
Compute the deletion amount per row/column — forced moves appear immediately.
Hex Mazes strategy for beginners →
Anchor from clues, fill gap-1 segments first, exploit edge cells.
Number Mazes strategy for beginners →
Find where the path is forced, not where it might go. Dead ends close first.
Square Maze strategy for beginners →
Corner cells have 2 neighbours — they force first moves before any gap counting.
Circular Maze strategy for beginners →
Inner rings are the most constrained — solve them first, outer rings follow.
Starlink / Hidato strategy for beginners →
Sort gaps by size, fill smallest first — they cascade and unlock the large ones.
Number Crossword strategy for beginners →
Count the digits in each expression before placing anything. Mismatched lengths are the tell.
Number Blocks strategy for beginners →
One empty cell = forced digit. Propagate across rows and columns.
HOW TO THINK
Sudoku: how to think →
Eliminate before placing. Think in units, not cells. The constraint mindset.
Killer Sudoku: how to think →
Think in cage options, not individual digits. 45-rule, then Sudoku scanning closes the rest.
Kakuro: how to think →
Why sum combinations matter more than arithmetic. The magic-sum table.
Calcudoku: how to think →
List every cage possibility before placing anything. Intersection does the rest.
Hitori: how to think →
How the three shading rules interact — and why each shade forces the next.
Takuzu / Binairo: how to think →
Three rules, one priority order — apply them in sequence to force every cell.
Skyscraper: how to think →
Edge clues are primary constraints, not tie-breakers. Start with clues 1 and N.
Shikaku: how to think →
Only place a rectangle when it's the only valid shape. Patience beats optimism.
Inequality / Futoshiki: how to think →
Trace full chains, not isolated clues — the extremes resolve first.
Countdown: how to think →
Start from the large numbers, not the small ones. Pattern first, search second.
Sumplete: how to think →
Compute the deletion amount first. Never delete without a forced reason.
Hex Mazes: how to think →
Six neighbours, one path — exploit edge cells and anchor from clues.
Number Mazes: how to think →
Work from clue anchors inward, not from start to end.
Square Maze: how to think →
Corners have 2 neighbours, edges 3 — boundary constraints drive every solve.
Circular Maze: how to think →
Rings wrap around — the inner ring bottleneck is where forced moves live.
Starlink / Hidato: how to think →
Diagonals count. Work the gaps between given numbers, corners first.
Number Crossword: how to think →
Evaluate the expression, count the digits, check leading-zero rule.
Number Blocks: how to think →
One empty cell in a row = forced digit. Cascade from there.
WHERE TO START
Which puzzle should I start with? →
Sudoku for logic, Kakuro for arithmetic, Mazes for paths. Pick your entry point.
Beginner mistakes in logic puzzles →
Five mistakes that look like the puzzle being unfair. They aren't.
Puzzle difficulty, explained →
What changes between an Easy and a Master puzzle — and when to step up.
COMPARE PUZZLES
Kakuro vs Sudoku →
Arithmetic-first vs logic-first. Same digit range, completely different constraints.
Sudoku vs Killer Sudoku →
Same grid, same three rules. Killer adds cage sums instead of starting digits.
Calcudoku vs Killer Sudoku →
Both wear cages. Only one has a 3×3 box rule. When to pick which.
Hex Mazes vs Number Mazes →
Same path puzzle, different cell shape. Six neighbours vs four — here's what changes.
Sumplete vs Kakuro →
Both use sum targets. Sumplete deletes given digits; Kakuro places new ones. Same destination, opposite start.
Hitori vs Takuzu →
Both are pure-constraint grids with no arithmetic. Hitori's three rules cascade; Takuzu's two don't.
Skyscraper vs Sudoku →
Skyscraper is Sudoku plus a ring of visibility clues. Same grid rules — an entirely different reasoning layer.
Starlink vs Number Mazes →
Both fill a sequential path from 1 to N. Starlink adds diagonal moves — four neighbours becomes eight.
Kakuro vs Killer Sudoku →
Both use cage sums. Kakuro has no Latin-square base; Killer Sudoku wraps cage sums around a full 9×9 Sudoku grid.
Number Blocks vs Sumplete →
Both match row and column sum targets. Sumplete removes given digits; Number Blocks fills an empty grid.
Inequality vs Skyscraper →
Both add one rule to Sudoku. Inequality uses comparison signs inside the grid; Skyscraper uses view-count numbers around the border.
Number Crossword vs Kakuro →
Both are arithmetic crossword grids. Number Crossword runs hold multi-digit numbers; Kakuro runs hold individual addends.
Countdown vs Calcudoku →
Both use +, −, ×, ÷ to hit targets. Countdown builds one free-form expression; Calcudoku fills a Latin-square grid by deduction.
Shikaku vs Hitori →
Both are Japanese spatial-logic puzzles. Shikaku divides the grid into rectangles; Hitori shades cells using three constraint rules.
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