Logic Masters Deutschland e.V.

This puzzle is based on an absurd puzzle I set for Turn 2 of the Skunkworks League event on Discord. The original was much less forgiving, much harder, and not as fun, so I've extracted some aspects of it I most liked. I hope you enjoy!

Rules:

- Draw a single closed railroad (loop) in the grid that travels both orthogonally and diagonally between the centers of touching cells.
- Within the grid, locate "islands" of orthogonally connected shaded cells.
- Different islands may not touch orthogonally.
- The railroad visits every shaded cell and does not visit any unshaded cells.
- The railroad visits every island exactly once, where a "visit" ends when the railroad visits a cell in a different island.
- Assign the following value to cells visited by the railroad: 1 for straights, 2 for obtuse angles, 3 for right angles, and 4 for acute angles. Circled clues on a diagonal outside the grid give the sums of consecutive cells visited by the railroad on their respective diagonal, in the correct order. No clued diagonal is missing clues.
- A "?" represents a single such clue.
- A blank circle represents any number of such clues, including none. - Different clues on the same diagonal must be separated by a cell not visited by the railroad.

Quite a mouthful, I know. I've set a solvable example puzzle to demonstrate the rules and to perhaps offer a chance to build some sort of logical foundation, should you want it:



Solve on Penpa (answer check on line only)
Solve on Sudokupad (no answer check)

The main puzzle:



Solve on Penpa (answer check on line only)
Solve on Sudokupad (no answer check)