The object of the game is to place all puzzle pieces on the game board so that the cutouts of each puzzle piece is placed next to the cutouts of other puzzle pieces. This way you create complete holes. It’s not allowed to create half holes except at the edge of the big square.
To make things more interesting, there are also 6 puzzle pieces with the artwork of a mouse. They act in a similar way as the pegs in IQ-Twist. But the difference with IQ-Twist is that you have to combine two pieces instead of 1 for each mouse. When you solve the challenge you will end up with a big square cheese with the mice looking through the holes.