Nice game I love the retro look&feel, but I've to say that I found 1 annoying thing, when you die the player is respawned just over the enemies and die again and again, it would be nice if you respawn the player in a safe place, for example on a formula's rectangle or inside a shield bubble or just respawn the player immortal for a few secs.
But overall, you have made a nice game, congrats!!