Very fun! I'll be sure to beat the high score :P
So, first thing, if you start a life spamming the fire button, you get no bullets. Bullets don't seem to work until you do the shield first.
Gameplay wise, I'm not sure why you're rewarding time with score. Rewarding time with score punishes the player for beating the level as fast as they can, because the game gets harder sooner compared to someone who lets the last guy float around until they reach the bottom.
Cool concept though, it's really fun.