Try every one of 16 possible shot types
Destroy 100 enemies with plasma
Destroy 100 enemies with electromagnetic pulse
Destroy 100 enemies with liquid nitrogen
Destroy 100 enemies with laser
Destroy an enemy at the last moment
Shoot at maximum power 100 times
Destroy 10 reptiloids
Destroy 10 insectoids
Destroy 10 robots
Destroy 10 siliconpazorps
Complete the game