Start the game normally, then press 'C' during game play. Ronny is immune to gravity. He can fly. Or type your name as "CHEAT" on the high score table and you will be able to fly and avoid the nasties. Another cheat says type "TRACTOR" into the high score table to be able to fly.

Try both of these: Entering your name as "RONNY" on the high score list or typing in "MICHAEL" when you die at the end of the game will give you the ability to fly. If this doesn't work, try pressing 'F9' to get all your energy back.