Logic Masters Deutschland e.V.

Normal sudoku rules apply.

Loop: Draw a one-cell wide loop of orthogonally connected cells in the grid. The loop may not cross or touch itself, even diagonally.

Circles: Circled cells lie on the loop. There is exactly one 9 on the loop, and it is in a circled cell.

Unfriendly cells: Digits on the loop are unfriendly: they may not equal the row, column, or box number they are in.

Skyscrapers: Each digit on the loop represents the height of a skyscraper in that cell. Each circled digit simultaneously indicates the number of skyscrapers that can be seen clockwise and counterclockwise from that cell along the loop. Skyscrapers hide shorter ones and those of the same height.

See the sample image for how the skyscrapers work.

Kropki: Digits in cells separated by a white dot must have values that differ by one.

Play in the CTC App

Example for reference: