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 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.
