Mathrax

Mathrax consists of a square grid. The goal is to fill in each cell with numbers from 1 to N, where N is the size of the puzzle's side. No number may appear twice in any row or column. Circles with additional conditions may be situated on intersections of lines inside the grid; a circle may contain:

Mathrax

Cross+A can solve puzzles from 3 x 3 to 9 x 9.