Logic Masters Deutschland e.V.

This puzzle is a variant of U-Bahn where you must shade some cells to form a loop, and then draw two networks—one inside the loop and one outside the loop. Difficulty estimated at 3½ stars. For an intro to U-Bahn with empty clues, see this 1-star puzzle by KNT.

Many thanks to wooferzfg, Jakhob, and KNT for testing earlier versions and providing valuable feedback.

Rules:

Shaded Loop: Shade some cells to form a single, orthogonally-connected loop. The loop is 1-cell wide and does not touch itself orthogonally.

2-Bahn (Two Networks)

• Draw two distinct loop networks—draw one network that occupies all unshaded cells that are inside the shaded loop, and draw another network that occupies all unshaded cells that are outside the shaded loop (networks cannot visit shaded loop cells)
• Each network travels through the center of cells, is fully connected, and has no dead ends
• A clue outside the grid indicates how many times the corresponding behavior (turn, straight, branch, cross, or unvisited) occurs in that row or column

For clarity, the shaded loop represents all cells that are unvisited by either network—there are no additional unvisited cells that are not part of the shaded loop.

Solve online:

• Penpa+
• SudokuPad