Bubble Bugs

Bubble Bugs are trying to destroy your base by moving across the screen from right to left and bombing the base when they reach the left side of the screen. You control an attack craft moving left or right below, firing missiles upwards to destroy as many Bugs as you can while avoiding their bombs. Firing missiles though uses fuel and to re-fuel you can either go back to the base on the left of the screen or wait till you run out and an rescue craft comes and re-fuels you. The rescue craft will also repair your craft if you are hit by a missile. There are 10 skill levels (1-10) with 1 being the slowest the Bugs move.