It is simple in the best way! Visuals are striking, Sound Effects are on point. It is fast paced in a way, that I restarted over a couple times after I thought, that I have already tried enough times.
Only point I could make is about my eyes being so focused on the bottom part of the screen, to catch the green area, that I didn't get to enjoy the visuals while playing as much. Maybe you could move it up a little bit and make it part of the scene.
Alien Invasion always works well!