Press and hold 's' to get the bat to drop down. Letting go of 's' will make him stop flying, and return to his "roosting" spot.

'a' and 'd' change the angle that he's flying at. Space-bar shoots lasers from the bat's eyes. It's pretty tricky to get the hang of... but gets easier over time!

In order to finish a level (there are 5 in total), all of the critters need to be killed by shooting them with the laser-eyes. The bat can then head to the exit (green-ish hole in the cavern).

Enjoy!