Only one thing
It's Space Invaders. It's a classic. What more is there to say? I like how you gave the options between the two as icing on the cake. I only have one gripe: I think the laser fires too slow (or the aliens move too fast at the end). By the time I'm down to one target I can get off an average of one or two shots before they've hit the bottom of the screen. I don't remember it being that difficult way back when I was a wee lad on a C64.