Logic Masters Deutschland e.V.

Normal Sudoku rules apply.

Cave Shading: Shade some cells in the grid such that all unshaded (cave) cells are orthogonally connected, all shaded (wall) cells are orthogonally connected to the edge of the grid, and no 2x2 is fully shaded or unshaded.

Counting Wallsweeper Circles: A digit in a circle indicates how many circles contain that digit. A digit in a circle also counts the number of shaded (wall) cells in the surrounding 3x3, NOT including itself.

Cave Sums: A small number in the corner of a cell gives the sum of all digits seen orthogonally from that cell, including itself, where cells of the opposite shading block vision.

(Click here to play the 6x6 example puzzle)

Solve on SudokuPad