Update: Trademark issues with the name caused the game to be pulled a while back, but now it's available again as "Super Crossfighter." Same game, new name and listing. Radiangames is also discounting its catalog to celebrate, so check that out. The original post below should still be accurate other than the name.
Video games make a lot of assumptions about aliens, mainly that they're going to be two-dimensional and prone to shooting at stuff.