Pretty awesome little game! It can be improved with very simple tweaks and I hope you update it.
Mostly you might need to work on the visual hierarchy - make the most important things for the player bigger and easily visible.
I think the loud music and the transparent timer in the middle were very distracting. The border could also be smaller since it's not a part of the gameplay. The enemies and projectiles are a very similar color to the background elements. Either remove the background or make them more easily recognizable. I know you're going for the 1 bit aesthetic but it would be cool if the enemies, or enemy projectiles are in color, for example.
Overall - very fun and with lots of potential! Good job!