FullHouse, also known as FullBoard, is a puzzle invented by Erich Friedman in 2004. The object of game is to draw a path through all the empty squares, passing through each exactly once. The path moves horizongtally or vertically, can only change direction when it hits a blocked square or the edge of the grid.
Tap on a square where you wish to start a path and then on a square in the direction of the desired move. The blue runner will always run straight, as far as possible, stopping only when blocked.