Same grid, no server
Most daily puzzles are downloaded. This one is computed: the date becomes the seed of the puzzle generator, and the generator is identical in every browser, so the grid on your screen matches everyone else’s for that date down to the last given. That is also why it works offline once the page has loaded, and why a shared daily link can be checked: the page rebuilds that date’s puzzle and only calls a link “the daily” when the grids match.
The week at a glance
| Day | Level | What it needs |
|---|---|---|
| Monday | Easy | hidden singles |
| Tuesday | Medium | naked singles |
| Wednesday | Medium | naked singles |
| Thursday | Hard | pointing pairs, pairs |
| Friday | Hard | pointing pairs, pairs |
| Saturday | Expert | XY-Wing, X-Wing, triples or Swordfish |
| Sunday | Hard | pointing pairs, pairs |
How the streak is kept
Your streak is the number of days in a row, ending today or yesterday, whose daily puzzle you’ve solved. It’s worked out from the list of solved dates stored in your browser, so finishing a day late still counts for that day. Your best run stays under the board even after a streak breaks. Solves with hints count for the streak; they just don’t set a best time for the level.
Racing a friend
The result card shows time, mistakes and hints, and Share result turns them into a link such as “I solved today’s Hard Sudoku in 6:12”. Your friend sees your time first, then gets the identical grid with their own timer, and the win card tells them whether they beat you.