Summation U-Bahn #3: Castle Wall
(Published on 17. October 2023, 09:00 by Agent)
Rules
- Draw a loop network through the centers of some cells, which may branch or turn, but may not have any dead ends.
- Assign each line shape (irrespective of rotation) a digit from 1 to 4 as follows: corner = 1, straight line = 2, branch = 3, cross = 4.
- Clues to the top and left of the grid indicate the sum of "digits" in each contiguous sequence of cells visited by the loop network, in the correct order. Consecutive sequences must be separated by at least one cell not visited by the loop network. For a given row or column, either all clues or no clues are given.
- Clues to the bottom and right of the grid indicate the number of cell borders crossed by the loop network in the respective row or column.
- Each letter represent a different number. A "?" may represent any number, including two-digit numbers.
Puzzle links
Solution code: For each row except the last, from top to bottom, the number of lines leading down from that row.
Comments
on 2. November 2025, 22:30 by Playmaker6174
It's unreal how distinctively breathtaking this puzzle is, and that's after solving so-called one of my absolute favorite u-bahn puzzles few days ago xD
Definitely the most challenging entry so far, but the logic at every major stage felt so different to other stages yet really cleverly and satisfyingly done too. Truly a towering achievement there! :O
on 5. October 2025, 14:57 by ddx02
I wanted to complete all 6 puzzles, before declaring a favorite, and this one is definitely it!
All puzzles were brilliant and fresh, but this one for me was the cherry on top.
on 11. August 2025, 17:38 by MaizeGator
I cannot believe that nobody strapped me to a chair and held my eyelids open and forced me to solve these summation ubahns in 2023. Two years later I am absolutely hooked and begging for more, which thankfully there are!
on 29. October 2024, 16:43 by MagnusJosefsson
Brilliant, like the rest of the series! Such solid and rewarding logic throughout!
on 27. October 2024, 19:14 by Piatato
Amazing puzzle, from start to finish!
on 7. October 2024, 23:14 by Christounet
Extremely good puzzle ! I got stuck forever on a step involving a very fundamental property of that ruleset... Now I need to let my brain rest before trying #4 ! Thanks :)
on 3. June 2024, 14:29 by zzw
Whoa, insane puzzle! Love how many things get forced in such interesting new ways.
on 26. April 2024, 16:06 by ibag
Absolutely fantastic!
on 8. March 2024, 17:30 by AnnaTh
Fantastic series! Took me a bit longer due to a persistent mistake. Could not let it go because it was so much fun!
on 27. December 2023, 18:34 by lerroyy
Very nice!
on 20. November 2023, 22:15 by Myxo
Wow, this was so brilliant! Wonderful solution path full of surprises from start to finish :)
on 25. October 2023, 02:55 by ONeill
Brilliant again. A great series!
on 20. October 2023, 07:18 by Jesper
A wonderful puzzle! Not easy but a lot of fun to solve.
on 20. October 2023, 02:13 by Agent
Fix solution code - apologies for the inconvenience.
on 17. October 2023, 16:25 by KNT
madness! my favorite of the three so far (though surely the most difficult for me).
