Your mission in this city-defense style shooter is to save the city and blast the flying saucers out of the sky. Make sure you don't shoot down the human escape ships, these will be awarded at 500 points each at the end of the game. Use YOUR MOUSE to aim and fire. Change weapon with the 1-5 NUMBER KEYS number keys across the top of the top of the keyboard. Each weapon has different strengths in different situations, so try them all out/ Ammo is displayed by the cross hair and under the gun icons. Ammo regenerates over time. Good luck!