It was published by Gargoyle Games in the United Kingdom and Dro Soft in Spain.

Because of this, it is often regarded as being part of an unofficial trilogy alongside Tir Na Nog and Dun Darach (both of which are part of the same official series) due to its having very similar gameplay to these titles.

Since the siege began, the Sept have been kept at bay by a huge Force Sphere which surrounds the Earth and the Moon.

However, the Sept are on the verge of discovering how to breach the Sphere unless it can be strengthened according to the formulae contained in the original plans.

[1] It was planned to be the first of the "Siege of Earth" trilogy, with its sequels "Fornax" and "Gath" were set for release in January and April 1986.