Bullet Train
by Jakhob and wooferzfg

This puzzle is a Permaculture that combines a Nurikabe and a U-Bahn.

If you are unfamiliar with U-Bahn, here is a guide that covers the core logic.


Divide the grid into two orthogonally connected areas. One of these areas is a Nurikabe puzzle, and the other is a U-Bahn puzzle.

Every cell in the Nurikabe puzzle is either water or land. All water cells must be orthogonally connected, and no 2x2 area may be entirely water. Clues must be on land cells, and every orthogonally connected area of land cells contains exactly one clue, the value of which represents the size of the area.

Draw a loop network through the centers of all cells in the U-Bahn puzzle, which may branch or turn, but may not have any dead ends. A clue outside the grid indicates 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.

9x9 Example Puzzle

Play the Example on Penpa+

Play the Example on SudokuPad

Puzzle Links

Play on Penpa+

Play on SudokuPad