That reminds me of something. In all games like this, humans (the player) always have a variety of sprites, but only one sprite for one type of alien. Can alien sprites be varied? We can vary the darkness (the tamans came in every value of grayscale! yay!), hue, size, etc. So that the player can distinguish one alien from the other: "that dark one is wounded, the taller one is still fresh"
Or maybe every alien is genetically identical?
Or maybe sprite varieties is useless because we cannot see it clearly on the screen. If that is the case please ignore this post.