Real Poltergeist

Gavin Raeburn made Poltergeist for Codemasters while working at AGC Systems but this is the game he wanted to make.

You are in control of an exorcist spacecraft and you must destroy a Poltergeist. Before this though you have to fly over 32 levels and destroy his minions and generators (flashing boxes). After each generator is destroyed you need to land on a teleport pad to get to the next level. There are plenty of weapon upgrades to collect to complete your mission by collecting Power Transmuters.