Watch movie 'Aliens' (alien 2) and tell me that isnt Starcraft?
Seems to me 'Aliens' 1986 (2nd movie in Alien quadrilogy) was the inspiration for Starcraft.
Watch the movie. It's a kick-ass space sci-fi action movie. Even for today, it's still great movie. You have space marines with gauss rifles firing away at incoming alien infestations. Just replace the famous ALIENS we know with zerglings (they even look similar) and there you go.
Watch 'Aliens' then think of making a STARCRAFT movie like that, only way better, and you have a huge summer blockbuster that will open up a whole new trilogy opportunity with tons of merchandise opportunities.