Colossal Cave U-Bahn
(Published on 29. April 2025, 09:00 by Agent)
Rules
- U-Bahn: In the left side grid, draw a loop network through the centers of some cells, which may branch or turn, but may not have any dead ends. Clues to the left and top of the grid 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.
- Cave: In the right side grid, shade some cells so that all unshaded cells are orthogonally connected, and all shaded cells are orthogonally connected by other shaded cells to an edge of the grid. Clues cannot be shaded, and represent the total number of unshaded cells that can be seen in a straight line vertically or horizontally, including itself.
- Interaction: Assign each line shape (irrespective of rotation) a digit from 0 to 4 as follows: empty cell = 0, corner = 1, straight line = 2, branch = 3, cross = 4. The "digits" in the U-Bahn grid represent the amount of unshaded cells in the corresponding 2x2 area of the Cave.
Example Puzzle (4x4, 8x8)
Main Puzzle (8x8, 16x16)
Solution code: For each row of the U-Bahn except the last, from top to bottom, enter the number of lines leading down from that row. Then enter the number of shaded cells in each of row 4, row 6, row 13, and column 11 of the Cave.
Comments
on 10. September 2025, 00:57 by cyddrdrd
Fantastic break-in!!
on 31. August 2025, 16:23 by lupo
Toll!
on 27. August 2025, 20:57 by ibag
This puzzle is absolutely unbelievable!!! Cool!!!
on 19. August 2025, 05:24 by MaizeGator
Absolutely outstanding. Very difficult break-in and midsolve for me, but breezy and smooth ending
on 10. August 2025, 17:36 by Piatato
Great puzzle!
on 30. June 2025, 03:09 by wisty
Lots of fun, thanks!
on 30. May 2025, 02:24 by BloodbuzzCorio
Not surprisingly another absolute masterpiece! Agent these puzzles you make which combine u-bahn and other rules are consistently very difficult but incredibly rewarding. Thanks!
on 14. May 2025, 12:13 by MagnusJosefsson
Amazing puzzle! Very cool combination with constant interaction between the grids.
on 11. May 2025, 22:17 by sfushidahardy
This was extremely difficult for me! But I loved every minute of the solve.
on 9. May 2025, 06:06 by KNT
awesome puzzle, especially the ending!
on 5. May 2025, 03:09 by askaksaksask
Fascinating puzzle. The interactions here are so rich. This is quite difficult i found, but much of the difficulty is concentrated in the beginning of the puzzle. Brilliant setting as well: there was a very good balance of cave, Ubahn, and "interaction" logic that guided the solve. Truly a blast to get through. This made my weekend! Thank you for the wonderful puzzle!!
on 3. May 2025, 11:29 by tuace
Klasse, und ein super Einstieg!
on 30. April 2025, 05:13 by CitrusGremlin
I'm sure this has nothing to do with the old text adventure Colossal Cave, but xyzzy anyways.
on 29. April 2025, 22:45 by Jesper
Epic and original puzzle!
on 29. April 2025, 11:45 by Christounet
Awesome opening and lots of satisfying deductions all the way. A very original evolution in the "colossal" serie. And certainly inspiring to develop other interacting grid puzzles. Thanks :)
