Midnight in New York, and the pages that move
The DleBox Krillion day ends at midnight in New York. The time zone is America/New_York, so that midnight is 05:00 UTC in winter and 04:00 UTC while the US is on daylight saving time. In New York it is still midnight either way. The daily seven, the hint page, and the live answer table all move at that moment. Practice does not become the new daily. A private rematch does not either.
The same instant is a different hour in London, Berlin, Shanghai, and Los Angeles, and those hours shift when the US or those places change their clocks. The reset page formats the next New York midnight in those zones in your browser, so the table does not go stale the night a region leaves daylight saving. China is UTC+8 all year. In winter the reset falls at 1:00 p.m. there, and in summer at noon.
Today's answers keep a single URL. Yesterday's answers keep a dated URL for fourteen days. We do not also file today under a dated path, because two URLs for one table is how a search result goes stale. The heading on the live page includes the date. A build once a day keeps the title and the new archive URL in the HTML. The countdown itself updates while the page is open.
krillion.io runs its own daily. This clock is for the version we host. The original game also counts a day from midnight in New York, which is why our date uses that city. The prompts are still theirs. Our directory states our clock next to our hosted game. It does not pretend to be their settings screen.
A game of the day on the homepage uses the same New York date as the seed for its rotation. That pick is a catalog game, not a Krillion prompt. The weekly chart uses the ISO week of that date. None of those pages change the seven prompts early.
From here you can see the reset clock. The Krillion directory page is the longer guide to the original game and to ours.
If you want the live countdown and the zone table together, use the reset page. If you only want to know whether the answers in front of you are still today's, look at the date in the heading and the countdown under it.
Other games on the list do not inherit this clock. A Times puzzle, a Teuteuf map, and a Merriam-Webster board keep whatever day their own sites use. The directory pages say so instead of inventing a second midnight. Only the Krillion we host is tied to New York midnight on purpose, and only the reset page tries to show that instant in other cities.
A page left open past midnight changes its heading in the browser. The title inside the HTML file changes when the site is built. That build also writes archive pages for the next 120 New York dates, so the day that just ended already has a file. The visible list, and the sitemap, still name only the past 14 days. Future dates are not linked from the answer page.
In winter, New York midnight is 05:00 UTC, 9:00 p.m. the previous evening on the US Pacific coast, 5:00 a.m. in the UK, 6:00 a.m. in Berlin, 1:00 p.m. in China, and 2:00 p.m. in Japan. In summer the UTC hour is 04:00, and China sees noon. The reset page computes those hours from the zone, including the nights the clocks change. It does not keep a fixed offset of five hours.