You're racing for the other black line! If you're playing the cat, then you'll press the right arrow key. If you're playing the beetle, then you'll press the d letter key. It can be two player or one player--if you're playing two player--don't freak out if you lose! It'a just a fun game that you can play again and again!
If you're having trouble, comment. I can see if I can fix it or do something about it.
