Outside Killer U-Bahn
(Published on 8. July 2025, 17:16 by the_cogito)
Rules:
- Draw a totally connected loop network through the centers of some cells, which may branch or turn, but may not have any dead ends.
- Cells in the spaces above or left of the grid may contain U-Bahn clues as allowed by other rules, where U-Bahn clues indicate how many times the corresponding line shape (i.e. a cross, branch, straight line, or turn) appears in the corresponding row or column, irrespective of the line shape's rotation.
- Given numbers outside the grid are killer sums, and function separately from U-Bahn clues. Killer sums indicate the sum of some group of orthogonally connected, non-repeating, non-zero U-Bahn clues. These groups must be found, must include their respective clued cell, and must not overlap with one another.
- Given cages in the grid may not contain the same line shape in the same orientation more than once.
- To activate answer check, correctly fill all U-Bahn clues which are part of killer sum groups, leaving other cells empty. Note that in sudokupad, emptying the other cells appears to be unnecessary.
Solve on Penpa+
Solve on SudokuPad
Solution code: For every column except the last, read from left to right, the number of loop segments extending right from that column.
Comments
on 15. October 2025, 14:39 by Christounet
Excellent and miraculous indeed. The way it resolves in the end cascasing through the grid is so satisfying! Impressive that this was done with only given numbers.
And with that puzzle, I have reached the milestone of my 500th 5 star puzzle solved on this portal! Thanks to you and to all the wonderful setters out there, making those delightful and intricate puzzles that have entertained me for so many hours.
on 24. August 2025, 01:42 by damasosos92
A real one-of-a-kind puzzle.
on 25. July 2025, 00:14 by BloodbuzzCorio
the_cogito this is an absolutely incredible puzzle. I am a huge fan of u-bahn variants and this is right up there with the very best of them. Thanks for setting and sharing!
on 20. July 2025, 10:13 by tuace
Great construction, magical and smooth :)
on 16. July 2025, 19:35 by Phistomefel
A wonderful puzzle and it is a very impressive feat to use just only the given numbers as clues. Kudos!
on 13. July 2025, 16:02 by Mr. Happy
Wow! What an amazing puzzle
on 9. July 2025, 22:51 by RJBlarmo
Incredible construction, and all the more impressive that this was created using 6 predetermined numbers!
on 9. July 2025, 21:37 by cyddrdrd
Smooth and brilliant!
on 9. July 2025, 19:40 by KNT
extremely impressive!
on 9. July 2025, 11:44 by Piatato
Amazing! You'd really think that you picked the numbers yourself. Almost unbelievably well done!
on 9. July 2025, 01:21 by Agent
Spectacular! One of the most impressive minimalistic constructions I've seen in a while, and yet the solution path is very entertaining and smooth.
on 8. July 2025, 21:46 by Jesper
Very cool puzzle, thanks!
on 8. July 2025, 19:08 by Niverio
Absolutely brilliant and magical construction!
on 8. July 2025, 18:06 by dumediat
For me, this puzzle was perfect in just about every possible way. Pure magic!
on 8. July 2025, 17:46 by sfushidahardy
Really amazing how smooth this puzzle was, given how difficult it looks. Loved every moment of the solve.
