I have to admit to being perplexed by Bug-Byte - the company is capable of releasing excellent budget games like Plan B, Hunkidory and even Dunjunz (bug-ridden though that one is!) at the same time as unleashing on an unsuspecting public such turkeys as Ice Hockey and Uranians that demean the whole budget concept.
This game is hardly worth bringing to your attention as I'm sure you will have at least one version of it already in your collection. Aliens, Mother Ships, explosions and so on belonged to an earlier era of Beeb games; why don't we leave them there if we can't rework them with some imagination, as in Galaforce?