Beautiful entry! Great idea and implementation, and art/music really compliment the gameplay! I'd say that it needs more balancing, right now there's no point to place anything but the weakest group of enemies, my longest run was when I placed only low-left enemy at about double of their timer frequency. But if the score is not the goal it's really fun to place the ships as many as you can and see how long our tipsy hero can last :)
Also great job on ships' movement/bullet patterns, it was a really nice touch to the game!