Lupin's Loop 6 - Between Worlds
(Published on 1. July 2026, 16:04 by Rab3aron)
Every loop he had solved was there: the city road, the space route, the island circuit, the underground metro, and the scattered fragments. Every choice, every mistake, and every moment of brilliance had been recorded. The aliens had not only been monitoring Earth. They had been monitoring him specifically.
The files revealed their true secret: for thousands of years, the aliens had been trying to connect the universe through a loop of teleportation portals. But when they tried to activate Earth’s portal, they faced a puzzle none of their greatest minds could solve.
The portal was powered by ancient alien energy cores, and to activate it, those cores had to be connected by one perfect closed circuit. But no matter how advanced the aliens were, their best minds could never find the route.
So they left Earth behind, but never stopped monitoring it. They waited for a mind brilliant enough to solve what they could not.
Then Professor Lupin appeared.
At the end of the file was a message addressed directly to him:
“We are watching you, Lupin. Finish what we could not, or humanity burns with the portal.”
There was no room to refuse. To save Earth, Lupin had to do the impossible.
Normal Sudoku rules apply.
Dots: Digits separated by a white dot are consecutive. Digits separated by a yellow dot are non-consecutive. Digits separated by a red dot must contain one even digit and one odd digit.
Cable: Draw a single cable that travels orthogonally from cell to cell, never branching, crossing, or overlapping itself, and eventually closes into a loop. The cable must pass through every electricity sign and may not cross rivers, represented by blue borders.
Segments: 90-degree turns split the loop into segments, including both endpoints.
Segment Counts: If a segment of length N exists, then the total number of segments of length N in the loop is M, where M is greater than 1 and M and N share the same parity.
Segment Endpoints: If a segment has length N, then the digit N must appear in one of that segment’s endpoints.
Purple Sensors: A digit in a purple sensor counts the number of loop cells in the 3×3 box centered on that sensor, up to a maximum of 9.
Marked Diagonals: Cells on the marked diagonals may not be part of any segment of length exactly 5.
Solution code: Digits on the loop in Row 3.
Comments
on 23. July 2026, 15:37 by amirs
Definitely the hardest one in the series thus far... :)
on 19. July 2026, 08:04 by barfurth
Truly amazing that these clues are sufficient to solve this.
Not sure that my solve had full rigor. At some point I found a way to complete the loop in a way that met all the stated and deduced constraints I found, without being entirely sure that I had actually ruled out all other possibilities.
I had apparently found the intended path, but I may need to go back to figure out, how I could have been completely certain...
Very much enjoying this L(oo/u)pin world!
Waiting for the next one to learn where the story goes next – and slightly hoping it doesn't get harder than this...
on 18. July 2026, 16:06 by xsansara
I had to restart a couple times, because I had gotten the path wrong and noticed much too late. Very, very hard.
on 7. July 2026, 16:47 by MasterVesuvius
The puzzle contains very interesting logic, definitely the most difficult in the series. Just the end feels like a leap of faith because of the number of possibilities you must wrangle to find the one which fulfils the ruleset. Thank you for all these puzzles so far!
on 7. July 2026, 01:36 by emoney1374
Incredible puzzle! Feels like there’s not enough info / rules but it’s there if you dig deep enough. Fantastic setting! 6/5 difficulty
on 5. July 2026, 21:07 by Fool on Hill
Beautifully done. It took a while to catch on to a key piece of logic and after that it unfolded ...
on 1. July 2026, 23:56 by harry_anthony
Amazing!
on 1. July 2026, 17:43 by luna_vale
Wow, this one was very hard, I really enjoyed the logic!
on 1. July 2026, 17:35 by mathics
Very beautiful puzzle! Great series!
on 1. July 2026, 16:17 by Vikkz
Brilliant puzzle! Solved this one while it was tested on stream and really enjoyed it!
