Summation Slitherbahn
(Published on 10. January 2026, 00:00 by cyddrdrd)
Rules
- Slitherlink: Draw a loop that travels along the edges of some cells that does not touch or cross itself. A cell's slitherlink number is the total number of edges surrounding itself that are used by the loop.
- U-Bahn: Inside the loop, draw a totally connected network through the centers of some cells, which may branch or turn, but may not have any dead ends. A cell's U-Bahn number is determined by its line shape (irrespective of rotations): corner = 1, straight line = 2, branch = 3, cross = 4.
- Summation: A cell's value equals the product of its slitherlink number and its U-Bahn number. Clues outside the grid represent the sum of values in each contiguous sequence of cells visited by the U-Bahn network, in the order of appearance from left to right or top to bottom. Consecutive sequences must be separated by at least one cell not visited by the U-Bahn network.
- Cypher: Each letter represents a different digit from 0 to 9. '?' represents any digit from 0 to 9. For a double-digit number, its first digit cannot be 0.
SudokuPad (no solution check)
Example puzzle:
Penpa+ (example)
SudokuPad (example)
Solution code: For each column except the last, from left to right, the number of U-Bahn lines leading right from that column; followed by size of regions outside the slitherlink loop in clockwise order, beginning in the leftmost cell of the topmost row.
Last changed on on 10. January 2026, 06:03
Solved by Christounet, MonsieurTRISTE, KNT, h5663454
Comments
on 10. January 2026, 06:03 by cyddrdrd
Estimated difficulty lowered to 4*
on 10. January 2026, 04:57 by KNT
Fairly tricky to start, but once you have a foothold, it feels like a 3 star difficulty puzzle.
on 10. January 2026, 00:03 by Christounet
Excellent puzzle ! So many cool deductions all the way. And a great twist of the summation u-bahn ruleset. Thanks :)
