This game is an unlicensed version of Stargate.
From the inlay:
The original 'Guardian' game was described as 'an amazing and fast moving space spectacular in the classic mould'. It was also considered by many in the home computer games industry as a standard by which others were judged.
Now Hi-Tec Software brings you the sequel, 'Guardian II', where the mutants really do get their revenge in this even faster and more amazing game that tests your skills to the limit.
Arcade and high score freaks, no need to queue here, just ooad up and hang on in there.
Guardian II is based on the arcade classic 'Stargate' (Defender II).