The aim is to fill in the blue figure: tap a blue tile to start then move horizontally or vertically by 3 or diagonally by 2 (possible moves are yellow pieces on blue tiles).
If you get stuck, you can undo the last moves to get back on track.
Train with the 20 different levels of increasing difficulty or play with the expert level that is the original game: 10 by 10 empty board.
10x10 is a variation of the Knight's Tour. High school students play it with pencil, paper and numbers instead of pieces.