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About this game
Regex Crossword is the read only regex puzzle the programming community plays every day. Each row and each column of the grid carries exactly one pattern clue, and the challenge is to place letters and digits so that every line satisfies its pattern at the same time. Nobody has to write a regex, you only ever read them. A dot stands for any single character, square brackets name a set of allowed characters, a caret inside the brackets flips that into everything except the set, plus and star and braces control repeats, and a vertical bar offers an either or choice. Twenty four puzzles across four chapters unlock the syntax in order, starting from plain letters and dots, moving through character classes, then quantifiers, and finishing with alternation, anchors and the greedy traps where a careless reading bites back. A line turns green when it matches, red when the letter you just placed contradicts it, and the card points at the first position where no letter can ever work. Long-press any clue card for a plain words explanation, three reads per puzzle. Mistakes decide the stars, zero wrong letters earns three, two or fewer earns two, and simply finishing earns one. There is also one shared 5x5 daily grid worldwide every UTC day plus an endless practice shuffle. The daily result copies as a spoiler free emoji card with row and column states and the mistake count, never the answer. Your progress is saved on your device.
How to play
Tap a cell to open the big letter keyboard, then tap a symbol to fill it. The row and column cards show the patterns. Fill the grid until every card turns green. Fewer wrong letters earn more stars.
Tips & Tricks
- Look at the anchors first, a caret or a dollar sign marks a forced start or finish, and in this game every clue has to match the full line anyway.
- Check the crossing clue before committing, one letter must satisfy the row and the column at the same time, the intersection is where the real constraint lives.
- A negated class flips the idea, brackets with a caret mean every character except the listed ones, so try the leftovers first.
- Long-press a clue card to read it in plain words, you get three reads per puzzle, save them for the line that stays red the longest.
Frequently asked questions
How do I know a puzzle has exactly one solution?
Every puzzle is constructed during development and then checked by an independent backtracking solver built on the same syntax engine as the game, which enumerates the whole board and demands that exactly one arrangement satisfies all row and column clues at once. The 365 daily seeds and the practice generator pass the same audit.
What does a red clue card mean?
The newest letter makes that clue impossible to complete, and the card marks the first position where no letter can work. Clearing or replacing the letter returns the line to normal, and the historical mistake count stays for the stars.
How do stars and the share card work?
Zero wrong letters gives three stars, two or fewer gives two, and finishing gives one. The daily challenge ends with a spoiler free card listing only the row and column states, the mistake count and the grid size.
