I present my first application.
It is the old game that when kids we used to play on a sheet of squared paper,
variosly named, magic square, 100 squares, ...
Using the same scheme, I have also added the knight move mode (i.e., touch
only one time every square of the board jumping like the knight of chess game;
in math, this is named an "hamiltonian path").
The first button shows the game instructions, but I think they are unnecessary.
Let me know your opinion about this app. Every advice obviously will be welcome.