http://www.maxgames.com/play/super-marine.html your supposed to keep killing those alien things that look like zerglings, and save up money to buy bigger weapons so you raid the alien base. obviously inspired by starcraft. any other space marine vs. alien games?
Hmmm well, the only one I can think of (since I'm not into flash games at all) is the flash version of Contra where your a commando taking on hordes of aliens and soldiers too in a side-scrolling shooter.
Unreal Tournament flash is pretty cool as well. -the new 2007 is the best flash version iirc- Not really Starcraft, but still a sci-fi flash game.