Regex Crossword is an offline puzzle game. Every line of the grid is a regular expression; fill the cells so that each line, read in its own direction, matches its clue exactly (a whole-string match). Features: * Three difficulties: Easy (rectangle 5x5), Medium and Hard (hexagon). Puzzles are generated on your device from a seed, so the number of levels is unlimited. * The hexagonal board has three colour-coded reading directions (X, Y, Z); the rectangle board uses rows and columns. Each clue shows its reading direction and start cell. * Tap a cell and use the on-screen keyboard. Pencil-mark notes, per-cell hints, "givens" (letters a clue writes down literally), undo/redo, and a per-level timer. * Progress is saved automatically for every level. Hard levels are pre-generated with a solver so that their answer is unique. No accounts. No ads. No network access. No permissions. Regex Crossword is free software under the MIT licence. The hexagonal "A Regular Crossword" form was popularised by Dan Gulotta (based on an idea by Palmer Mebane) in MIT Mystery Hunt 2013. This app is an independent implementation and includes neither the original puzzle nor its text. Source code: https://github.com/CuSO4Deposit/regex-crossword