Lupin's Loop 2 - Space Invasion
(Published on 26. May 2026, 08:39 by Rab3aron)
Then they heard about Professor Lupin’s impossible road system in the city. NASA’s scientists laughed when his name came up. They doubted the stories from the city, and doubted even more that Professor Lupin could solve an expedition their own calculations had failed to plan. But with the mission nearly abandoned, even a ridiculous rumor was worth testing.
With nothing left to lose, NASA prepared a final test. A sealed envelope arrived at Lupin’s door, holding a star map, a list of black holes, and one mocking message: “Loop it, Lupin.” Now NASA was about to discover whether Professor Lupin was truly a genius… or only a very convincing rumor.
Normal Sudoku rules apply.
White Kropki Dots: Digits separated by a white Kropki dot are consecutive.
Route: Draw a single route that travels orthogonally from cell to cell, never branching, crossing, or overlapping, and eventually closes into a loop. The loop must pass through every planet.
Black Holes: Thick black borders represent black holes that the route cannot cross.
Satellites: A digit in a satellite equals the number of loop cells in the 3×3 box centered on that cell.
Parity: Along the loop, one parity forces the route to turn, making a 90° angle, while the other forces it to continue straight, making a 180° angle. It is up to the solver to determine which parity corresponds to which behavior.
Non-consecutive Along the Loop: Any two cells that are adjacent along the loop must contain non-consecutive digits. The only case where consecutive digits may appear along the loop is if the loop passes through a white Kropki dot.
Solution code: Digits on the loop in Row 3 from left to right.
Comments
on 15. June 2026, 20:56 by Quizzmo
Very nice! Closer to 3* for me though. Love this series :)
on 31. May 2026, 18:38 by psams
I enjoyed solving this - thanks for creating it and adding a story around the abstraction. One very small issue I had was the word "may" regarding the white dot on the path put some doubt in my mind until I reread the start of the instructions - would have been helped had the Kropki instruction come at the end.
This solve has two distinct halves - it might have been interesting to leave some ambiguity in the loop that would only resolve by the sudoku deductions.
Coincidentally, I published a puzzle the day before this one with a sci-fi theme, combining drawing lines and filling in the numbers, "Dome 19" - very different logic though.
------------
Hey, thanks for the feedback! Actually the next puzzle in the series has some ambiguities that can be resolved only after placing some digits :)
on 28. May 2026, 18:24 by highonlife
Brilliant!!
getting started was the hardest part, after that it was fairly smooth.
on 28. May 2026, 06:42 by pmays123
This solve felt like two brilliantly crafted puzzles somehow packaged into one! Thank you so much for sharing this masterpiece.
on 26. May 2026, 22:04 by waxy
smooth solve, enjoyed the read as well. very beautiful and well designed puzzle.
on 26. May 2026, 16:45 by wuc
I tend towards to 4*. Brilliant construction. Awesome to solve thx.
on 26. May 2026, 16:21 by Zibl
Lovely puzzle! Thank you!
on 26. May 2026, 12:28 by philolologue
Looks fun! Quick question before starting, can the loop touch itself? So can it make a U-turn in a block of four cells for example?
-------------
Hey, yes it can touch itself, as long as it doesn't branch or overlap it's fine
on 26. May 2026, 11:50 by Vionix
Very smooth and elegant solve! I really enjoyed the background story as well. 3 stars for difficulty from me.
on 26. May 2026, 11:12 by blueberrypug
closer to 4 for stars for me
on 26. May 2026, 10:16 by mathics
What a masterpiece! Absolutely loving this series, can’t wait for more :)
on 26. May 2026, 09:45 by 6yler
What a brilliant and smooth puzzle!
on 26. May 2026, 09:41 by luna_vale
Brilliant puzzle! Very beautiful break in and a very smooth solve path!
