Hey guys so basically this is a race. You should play this with another person. So if you're the dog, when the cat says 'Go!' you press the 'M' key, and if you're the bat, do the same thing just press the right arrow. When someone wins, the animal he/she is will automatically go to the start. The loser, must continue to go forward until the player reaches the balloon. Play as many times as you want.
Credit to Jon Woodcock and his book <Coding Projects in Scratch>.