Logic Masters Deutschland e.V.

Hello

Normal Sudoku rules apply.

Dutch Flat Mates: Every 5 in the grid must have a 1 directly above it or a 9 directly below it. It may have both, but it doesn't need both.

Columns 1, 5 and 9 are column indexers.  A digit N in column 1 indicates that 1 is in the Nth column of its row. Same for columns 5 and 9 respectively.

Additionally, row 5 is a row indexer. A digit N in row 5 indicates that 5 is in the Nth row of its column.

Digits on an arrow sum to the digit in the attached circle. 

                                                          click image to play in sudokupad