Players move alternately.
On the first move, Player 1 takes any piece from reserve and puts it on the board. Then he takes another piece and puts it on special 'move now' square. On subsequent turns, you first move the piece on 'move now' square to any square on the 4x4 board, and then put new piece on 'move now' square.
 
You win if you create a 'quarto' - i.e. line of four pieces (or a 2x2 square in some variants) which share any one characteristic - shape, size, color or if there is a hole in them.
 
Variant 2: 4-in-line or 2x2 square wins
Variant 3: 4-in-line loses
Variant 4: 4-in-line or 2x2 square loses