Thanks James! Good tip on the slowdown. I will work on that. It's nice to hear comments about this, because I had gotten used to the mechanics, haha!
As for the health indicators, I do have the character sprite change as it gets damaged. But it is subtle. I could use something like a heart GUI to make it clear. And now that you mention it, it'd be cool to keep track of how many aliens were picked up and maybe factor that into a score at the end.