The instructions are at the beginning. When you click the mouse, Scratchy(the cat) will follow you. Keep the letters(V, I, R,U, and S) away from the server. If the letters touch the server, then you lose a life(the variable is called chance) Reach a score of 30 to win. When you are out of chances, you lose, but you can try again.
This came from the book "Super Scratch Programming Adventure". It's a book that teaches you programming by doing a step-by-step tutorial for each game. This is what inspired this program and many others.