Logic Masters Deutschland e.V.

Normal Sudoku rules apply. In addition, cells which are connected by a toroidal knights move (cf. below for explanation) cannot contain the same digit. Moreover, all three "diagonals" (in the toroidal sense)—as indicated by the three different colours—contain each of the digits from 1 to 9 exactly once.

With respect to the anti-knight and diagonal constraints, the grid is to be considered toroidal, i.e., we imagine that each pair of opposite boundaries is glued row by row and column by column, respectively.

The "toroidal anti-knight" constraint says that two cells which are connected by a knights move cannot contain the same digit, but since the board is toroidal, knights moves across the boundary of the grid are permitted, reentering the grid in the respective row or column. E.g., moving "two cells upwards and one cell to the left" from the cell r1c2 means crossing the northern boundary, landing in row 8, yielding position r8c1. Altogether, the cells which are connected to r1c2 by a toroidal knights move are: r9c4, r2c4, r8c1, r8c3, r2c9, r9c9, r3c1 und r3c3.

Solve on penpa+ or f-puzzles.com.