Logic Masters Deutschland e.V.

Here is another U-Bahn hybrid, using an interaction with a Chaos Sudoku. I considered making the puzzle a "colossal" one, with a 9x9, but I feared the U-Bahn scanning would be a bit painful with that ruleset on a 27x27 grid... So I settled on making on a smaller grid with a 6x6 sudoku, which creates some interesting patterns in the U-Bahn grid. I may consider setting a colossal one with some modifications of the ruleset if this one is appreciated. Estimated difficulty around 5 for the opening, lowering afterwards. Enjoy :)

The puzzle :

Play on Penpa (answer check with green lines for the U-Bahn, blue digits and green region edges for the Sudoku).

Rules :

Standard U-Bahn : 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 above 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.

Chaos construction sudoku : Divide the 6x6 grid into regions, each consisting of 6 orthogonally connected cells. Each row, column and region must contain the digits 1 to 6 once each. The digit in each cell must equal the number of cells visited by the U-Bahn loop in the corresponding 3x2 box of the U-Bahn grid.

Clues (sudoku grid) : Digits in cells with arrows indicate the number of cells seen in the indicated directions combined, including itself. Cells that belong to different regions block the view.

Example puzzle :

Play on Penpa (answer check)

Note : the shading of the U-Bahn and corner pencil marks are not needed for the solve or answer check. They are a way of notating that I use while solving this kind of puzzle. It might come handy if you are not used to solving U-Bahn.