Play as the bat and use the up and down arrow keys to avoid the stalactites and stalagmites. When you progress enough you'll find the demon bat boss. Use the space bar to attack him and try to avoid his fireballs!
This is probably my most advanced project I've made so far. It uses scrolling, attacking bosses with HP, and maneuvering through obstacles. It was going to have a credits sequence, but for some reason none of the broadcasts for the credits would work.