Zub

Zub is a computer game made for use on the Commodore 64 and ZX Spectrum computers which was released in 1986 by Mastertronic. The code was written by John and Ste Pickford on the ZX Spectrum and Phillip Brian Allsopp on the Commodore 64, and the music was composed by David Whittaker.
The plot of the game.
Zub works for the Emperor Zub of the Zub galactic empire and must find the Green Eye of Zub. Zub has been permitted to use the Ancient Intergalactic Elevators which take him to other planets. The elevators can only be reached by jumping and riding on platforms to reach the top of the sky. The platforms and elevators are guarded by creatures (also known as Zubs) but each planet has a different sub-species - for example the first level's Zub resembles a gyroscope whilst he fourth level Zub is a fish. The Zubs can be shot and stunned. They will float to the top of the sky where the recover and return to attack Zub again. The Green Eye of Zub was located on the tenth planet and once the Eye is found, Zub has to return to the first planet to give the Eye of Zub to Emperor Zub.
There are seven difficulty levels, each one increases the number of enemy Zubs per planet.