Damn, this game looks great. The retro style was done pretty much perfectly. It's simple gameplay-wise, but well executed. Love the slow buildup, and how the space closes in slowly until you kill an enemy.
I think the only two issues I had were that the player hitbox is a bit too large, it could probably be made a little smaller, and that while the player getting redder the more damage you take looks good, I think if there was an actual health bar it'd make the amount of health you had left more understandable.
Overall a really good game! Very solid entry.