Tempest is a 1981 arcade vector game by Dave Theurer that was released for the CPC in 1986.
The arcade game is played with a spinner, the CPC is played with the joystick or keyboard of course, which is not quite as fast. Still, the overall feeling of the arcade game is matched nicely by the CPC port and the vector graphics are fast and colourful.
You are controlling a Zapper which moves around the rim of a 3-D tube. Enemies enter from the far side of tube and must be shot, ideally before the reach the near side. Not all positions around the rim are equally safe because the angle between the faces determines how the enemies can move. So in some positions on the rim enemies can reach you from the side and in others not.
When you are done with one tube, you warp towards the far side and enter the next tube with a differently shaped rim. There is also one Super Zapper per tube that destroys all enemies at once.