You will be given a target number at the start of your game.
There are four crystals below.
By clicking on a crystal, you will add a specific amount of points
to your total score.
To win the game your total score has to match target score, if your score goes
over the target score, you lose.
The value of each crystal is hidden from you until you click on it.
Each time when the game starts, the game will change the values of each crystal.