The daily set
Every day, the drill picks three tactics puzzles near your current level from a pool drawn from the Lichess Open Database. The set is fixed for the day: everyone who plays on the same day with the same history sees puzzles shaped by their own record, not a global list. Puzzles you have already solved are not served again until the pool has been worked through.
What counts as a miss
Solve a puzzle without a wrong move and without the hint, and it counts as clean. Need a hint, make a wrong move, or ask for the solution, and the puzzle still counts as finished — but every tactic in it (its fork, its pin, its mate pattern, and so on) is noted on your weak-point list. The list is not a punishment; it is the drill's memory, and it is what tomorrow's selection reads.
How tomorrow leans in
When the next day's three puzzles are chosen, puzzles containing your weak tactics score higher — the more often you have missed a tactic, the stronger the lean. A clean solve pushes back the other way, counting against the misses. The lean fades with time: a miss from more than about two weeks ago counts for less than yesterday's, so the drill follows your current weaknesses, not your ancient ones. Your estimated level also moves a little with each result — up after clean solves, down after shown solutions — which keeps the daily three near the edge of what you can almost do.
Streaks
Finish all three puzzles and the day counts toward your streak. Miss a day and the streak restarts — the weak-point list, however, is kept, so returning players pick up against the same weaknesses they left.
Your data stays yours
There is no account and no sign-up. Your drill history — weak points, level estimate, streak, solved puzzles — is stored only in this browser's local storage, on this device. Clear your browser data and the drill forgets you completely; nothing about your play is sent to a server.
Where the puzzles come from
Puzzle data: the Lichess Open Database (database.lichess.org), released under CC0 1.0 — free for anyone to use, including commercially. Thank you to the Lichess community. The tactic guides on this site use positions from the same database, each with a written explanation of the pattern it teaches.