Nice game. I like how you chose the screen size to fit the shooter style of the game.
I had a bit of trouble understanding what inverting the ship did at first, and I'm still not fully sure how the red life is gained back.
The game also seemed to slow down at some point (I was at about 140 score). The music kept playing at normal speed, but enemy and player movement were slowed by maybe half, not sure why!
Loved the presentation, minimal (but not minimalist) looks with a nice colour palette, and a catchy 8-bit tune.