Daily Puzzle
One puzzle per game, the same for everyone, rolling over at midnight US Eastern. These are the app's own boards — the website derives them from the same date and seed rather than fetching them, so nothing here needs an account or a connection.
Read-only. Results are not submitted and there is no leaderboard here — the app owns that. Smart Hint is also unavailable on a Daily board: the site ships no recorded solver line for these, so there is nothing to name a technique from. Plain Hint works, since it needs only the solution.