Logic Masters Deutschland e.V.

Rules
Shading: Shade some cells so that no two shaded cells are orthogonally adjacent. In a cell with arrow(s), the arrow clue(s) point in all directions which are tied for the closest shaded cell (arrows can see through other clued cells). Cells with arrow clues cannot be shaded. It is permissible for a shaded cell to have no clue pointing at it.
Ring-ring: Draw some rectangular loops through the centers of the empty cells so that every empty cell has at least one loop passing through it. The sides of different rectangles may intersect each other, but not turn at their intersection or otherwise overlap.

Here is a small example to illustrate the rules. You can try solving the example online in Penpa+ (with answer check on shading and green loops), or Sudokupad (no answer check).

Solve the main puzzle online:
Penpa+ (with answer check on shading and green loops)
Sudokupad (no answer check)