Rack Flip
A daily lights-out logic puzzle: tap a panel to flip it and its neighbours until every panel on the rack is green.
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Rack Flip
Today's rack is on its way.
Today's rack
0/25 green · 0 taps · Time 0:00
- Green: panel up
- Dark with a red LED: panel down
- A tap flips a panel and its four neighbours
Tap a panel to flip it and its four neighbours. Make every panel green.
Clear the rack to file your taps and time.
Next rack at midnight UTC.
How everyone did today appears here once 20 players have finished.
0Cleared
0Streak
0Best streak
–Best 5×5 taps
–Best 6×6 taps
–Average time
Today's card shows the rack as it starts, your tap band, streak and the days to launch; a card for an earlier day shows that day's rack all green. Never today's answer.
5×5 on weekdays, 6×6 at the weekend, a 4×4 warm-up, one hint, a streak, personal bests and a spoiler-free result to share. A fan puzzle, not a status signal.
How to play
The rack is a grid of panels, some green and some dark. Tap a panel to flip it together with the panels directly above, below, left and right of it; the rack is cleared when every panel is green. Tapping a panel twice undoes it and the order of taps never matters, so the puzzle is about which panels to tap, not when. Undo takes the last tap back and Clear restarts the rack. Every rack is checked when the site is built to have exactly one lightest tap set within the size's tap bound (at least three and at most seven, nine or thirteen taps on the 4×4, 5×5 and 6×6), found by GF(2) elimination of the flip operator, so the fewest-taps grade is always fair.
Tip one: chase the lights down. Work row by row from the top: for every dark panel in the top row, tap the panel directly below it; the top row is now all green. Repeat for the second row, and so on, until only the bottom row can still be dark. Tip two: the bottom row tells you where to start. Whatever pattern is left in the bottom row after chasing is fixed by a few taps in the top row and a second chase. On the 5×5 there are only a handful of bottom-row patterns that can appear, and each pairs with one top-row fix; on the 6×6 the chase from any start lands on the answer straight away. When a chase leaves you with more taps than the fewest, Clear and try a top-row tap first.
Everyone gets the same rack on the same UTC day: 5×5 on weekdays, 6×6 at the weekend, and newcomers can switch on the 4×4 warm-up, which still counts. One hint a day taps one panel from the lightest answer for you and marks the result as assisted. When the last panel turns green the rack lights up panel by panel and the status board signs off with your taps and time. The archive lets you play any earlier day's rack and practice racks come from a spare pool; both are marked and never count. Rack Flip is a fan puzzle on an imagined rack; nothing here reports the state of any real service, and nothing is presented as official. For a connect-the-pairs puzzle try Signal Path; for a tile puzzle, Packet Pipes.
Questions
What are the rules?
Every panel on the rack is green (up) or dark (down). Tapping a panel flips it and the panels directly above, below, left and right of it. The rack is cleared when every panel is green. Every rack here can be cleared, and each has one lightest tap set, so the fewest taps is a fair target.
Does the order of taps matter?
No. A tap only ever flips the same five panels, so tapping a panel twice undoes it and the order makes no difference; what matters is which panels you tap. That is why the fewest-taps answer is a set of panels, never a sequence.
How are taps counted?
Every tap counts one, Undo takes one back and Clear sets the count to zero. Your result is the tap count you finished with, graded against the fewest possible: the fewest, within 2, 5, 10 or 20 of it, or more. One hint a day taps one panel from the lightest answer for you (it counts as a tap) and marks the result as assisted.
What is the warm-up?
A 4×4 rack for newcomers, switched on with the Warm-up toggle (remembered on this device). It counts as the day's solve; the 5×5 weekday and 6×6 weekend racks are what the best taps and the Clean Rack card are about.
Is any of this real?
No. Rack Flip is a fan logic puzzle on an imagined server rack. Nothing here reports the state of any real service or rack; for that, see the live status page.
Keep exploring
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Incident historyEvery period in the last 30 days when an official status page reported a problem, or when a service stopped responding…