Encounter!

Encounter! is a fast paced arcade game set in a sci-fi environment which features fast moving three dimensional graphics. You command a probe vehicle with which you have to shoot down enemy saucers and homing missiles. When you have shot down the required number of enemies on one level (usually around 10-20) you get the chance to go through a "stargate". In the stargate you have to navigate through a hail of spheres coming at you at high speed. If you succeed you get to a new planet in different color scheme, if you fail you'll have to replay the previous planet. There's eight levels in total.