CrossFire - 1.0

Blast the invading alien scum to bits with your two trusty drone weapons. You control both at once, using the left and right cursor keys to control the bottom drone, and the up and down cursor keys to control the side drone. 'Z' fires the bottom drone's weapon and 'X' fires the other. You have a shield that can take 9 direct hits either from an attacking alien or one of their lazer blasts. There are 9 waves of aliens to show just who is boss. The code is a bit messy as I am currently learning Python and PyGame. I plan to improve it, with the introduction of Sprite Groups first on the agenda. I will upload changes as I make them.