Nice little banger of a soundtrack there, it slaps! I thought the enemy designs were cool, that shifting red eye on the large green dudes reminds me of the Cylons. The eye enemy at the end looked cool as heck and I thought the explosions were excellent. I think the inclusion of a playtest mode was a fantastic idea that I will implement in my own projects in future, very smart. The main screen is beautiful and hypnotizing.
One sentence review: "Playtest your way to victory and ride this wave to the very end"