Logic Masters Deutschland e.V.

• Normal sudoku rules apply.
• The grid is projective: each edge of the grid is considered to be adjacent/orthogonal to its diametrically opposite edge. (For example, r2c1 is considered orthogonally adjacent to r8c9.) Lines wrap around diametrically opposite sides of the grid.
• The 3x3 regions cut a blue line into connected components with the same sum. That same sum may differ between different lines.

Online in Sudokupad

For a true immersion onto a non-orientable space, check out DubiousMobius' Klein's Foggy Glasses.