Questions, corrections and bug reports are all welcome. Email is the only channel — there's no form, no ticket system and no chatbot.
I read everything and reply to most things, usually within a few days.
If a puzzle appears to have no solution or two solutions, please include the puzzle number shown above the board, the difficulty level, and the date if it was a Daily Challenge. That's enough to reproduce the exact board. Puzzles are verified for uniqueness before being served, so a genuine failure would be a real bug and I'd want to fix it quickly.
Your browser and version, your device, and roughly what you were doing when it happened. A screenshot helps more than a description.
If there's a technique you'd like written up, or an existing guide that skips a step you got stuck on, say so. Gaps in the explanations are the most useful thing anyone sends.
Use the same address and mention the subject in the first line.
Emails are used only to answer the message you sent. Nothing is added to a mailing list — there is no mailing list. See the privacy policy for how data is handled on the site itself.