How long a reply takes
Two people run this site around other work, so treat two to three business days as the realistic window for an answer, and a little longer in the weeks either side of a holiday. Everything is read. Not everything is answered: if you report something broken and the repair takes an hour, we would rather spend the hour on the repair than on a note promising one. A puzzle that quietly starts working again is what a reply looks like in that case.
If a week goes by with silence on something that clearly needed a response, send it again. Mail does get lost, and a second message never annoys us.
Reporting a puzzle that looks unsolvable
This is the report we care about most, because a grid with no valid ending is a failure of the generator rather than a cosmetic glitch. It is also the report that is hardest to act on without detail, since every board is generated fresh and we cannot open the one you were looking at.
Four things make it reproducible. Name the puzzle and the difficulty you had selected, because the generators behave differently at each level. Tell us the browser and version and whether you were on a phone, a tablet or a desktop. Copy the exact line the status bar under the board was displaying when you got stuck — that text is the clearest signal we have about what the puzzle thought was happening. And describe the last two or three moves you made before it went wrong.
If you can, add a screenshot of the board. A picture of the grid lets us type the same position into our own solver, which usually settles the question in minutes. Should your browser have a developer console open, any line in red belongs in the message too.
Worth checking first: on Sudoku and Pixel Logic a board can feel unsolvable and still be perfectly sound, because one earlier entry contradicts the rest. The Check button, where a puzzle has one, will tell you that faster than we can. If Check reports no conflict and the board still cannot be finished, that is a real bug and we want it.
Suggestions and corrections
Puzzle suggestions do shape what we build, with two limits worth knowing up front. We only implement puzzles whose rules are free for anyone to write, which rules out anything tied to a licensed property or a commercial product. And every board has to be playable with one thumb on a small screen, which quietly excludes a lot of otherwise good ideas.
For a correction, quote the sentence you think is wrong and say why. We would rather change a paragraph than defend it, and corrections are credited on request. If a difficulty estimate in a guide is nowhere near your experience, that counts as a correction too.
What not to send
Please keep passwords, card numbers, government identifiers and anything else sensitive out of a contact form; email is not a secure channel and we have no use for that information. We also decline guest posts, link exchanges, "sponsored article" offers and anything asking us to place a paid link in an existing guide, so those messages will not receive an answer. Bulk mail sent from a list gets deleted unread.