Nice arcade game! For some reason the level reminded me of snow bros.
It's easy to pick up and play and the sprites are lovely.
Sound would be a great addition to this. The gameplay is pretty solid, I think you could remove the "safe spot" at the top though haha, because it makes the game so much easier (there is a platform that no enemies can reach). The design as it is incentivizes you to stand at one place and shoot carefully.
I want to make something in Pico 8 eventually, it seems super interesting. Good job with the game!