Dokusu is part Sudoku, part slider puzzle with a math lesson on the side. It borrows from both the enormously popular Sudoku and from classic slider games like 15-Square, but adds an interesting topological twist. Play it for fun or use it as an educational aid to explore permutation group theory concepts.

Using touch-and-drag, move the tiles horizontally and vertically to form a 4x4 Sudoku square. Moving a tile horizontally causes all the tiles in that row to shift circularly. As tiles move off the board on one side, they enter the board on the other side. Similarly, moving tiles vertically causes columns to shift circularly.

Dokusu is simple enough to be played by elementary school children, but challenging for all ages. Basic and advanced level math discussion material is included. The basic math concepts are suitable for everyone and the advanced math concepts are targeted at upper high school and undergraduate college level students. A special advanced mode facilitates mathematical experimentation.