Great job! Love the look of the game and I like the unique input scheme, but I think that I stopped liking once the last wave started, haha. If I could suggest something, instead of making it to shoot with just a click, I think you could still retain the interesting input scheme and make it more enjoyable by allowing the player to select mulitple asteroids at once and with just one press of the spacebar shoot missiles to every selected asteroid. Could add a select cap to keep it a bit harder as well, but yeah overall a great submission!