Logic Masters Deutschland e.V.

Rules:

Normal sudoku rules apply

Cells joined by a white dot have consecutive digits. Not all possible white dots are given.

Castle Walls:
Draw a loop that moves orthogonally, it can touch itself but not cross itself or cover a cell more than once.
• Cells marked with arrows, circles or squares may not be on the loop.
• Cells marked with circles must be inside the loop, cells marked with squares must be outside the loop.
• A cell with an arrow contains a digit that indicates the number of line segments in that direction (i.e. the number of times the loop crosses a cell border traveling in that direction). Vertical arrows only count vertical lines, and horizontal arrows count horizontal lines.

Mod-length Region Sums:
The loop is a mod-length region sum line:
• Box borders split the line into connected components.
• Cells on a component of length L with a digit D have a value equal to the remainder of D divided by L. (If D is a multiple of L then the cell has value equal to 0.)
• All components have the same value sum.

Below is an example of a valid loop: