Reminds me a bit of mini-metro. Didn't seem like there was any point to not be glued to the operator panel, so it might be best to re-jigger the game so that you're always just moving the elevator up and down rather than be able to walk around for a reason I couldn't really tell.
Would also help the strategy if you could see all the floors. As is, you're just kind of guessing on where to go to.
A different perspective (anthill style) and controls that always focused on what you had to do would help a lot.
Aliens have a lot of personality and charm. :)