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