To play you use the mouse to click on the alternatives you think is correct.
The are no penalties for choosing wrong (unless you count a negative sound) and there are no rewards for choosing right except a positive sound. If you get all the way to the end, you get another "reward".
The purpose of the game is to help the player memorize the alphabet.
This site is static. That means, for instance, that the options for the first letters are always going to be "A", "I", "S", and "V".