Coilu is a cage-arithmetic logic puzzle you can play entirely offline. Fill an NรN grid so that every row and every column contains each number from 1 to N exactly once, then satisfy the outlined "cages": each cage prints an arithmetic target and an operator (+, โ, ร, รท), and the numbers you place inside it must combine to hit that target. It is a Latin square with an arithmetic twist โ from the KenKen family, and deliberately not Sudoku.
Every puzzle is generated on your device ๐ฑ by a genuine engine: a Latin-square generator, a cage carver, and a backtracking solver that guarantees each puzzle has exactly one solution and rates its difficulty ๐ by how much deduction it demands. There is nothing to download and no half-baked boards โ only solvable, uniquely-determined puzzles across four grid sizes (3ร3 up to 6ร6) and four difficulty tiers, from Easy to Expert ๐.
Tools ๐ ๏ธ that make solving feel good:
โข Pencil marks for candidates, with optional auto-cleanup when you place a final value
โข Live conflict checking that flags a repeated number ๐ข in a row or column, or a cage that misses its target ๐ฏ, the instant โก it happens
โข Undo, erase and reset, plus a calm, non-punitive timer
โข A first-run tutorial and a LEARN ๐ section with real techniques and an interactive demo cage you can tap ๐ through
Track your play โถ๏ธ in RECORDS: solved counts and best times per size and difficulty ๐, a solve-time โฑ๏ธ visualization, and a Trophy Wall where you can attach a personal photo ๐ธ โ taken with your camera or picked from your gallery โ to each difficulty you have conquered. Every puzzle also carries a short seed code, so you can reopen an exact board later or hand one to a friend, all computed locally.
Coilu keeps everything on your device ๐ฑ: no accounts, no ads interrupting a solve, and no network needed to play โถ๏ธ. If you enjoy Latin squares, KenKen-style math ๐งฎ cages, or simply a quiet, honest logic puzzle, Coilu gives you an endless, always-fair supply.
Offline ๐ด cage-arithmetic number ๐ข puzzles with a real unique-solution engine.