I liked the little Japanese voice; I think that is a nice touch. I also thought the sound effects for shooting were pleasant and not annoying. I could totally see this having a synth-wave soundtrack.
What would improve it was if there was text on the screen explaining the controls, and some time to actually move the ship before enemies start hugging you? I like the minimalist UI, but having something explain things before disappearing would be very helpful.
Unfortunately, I'm unsure if I'm doing it wrong, if something is wrong with my janky computer, or if I just can't move my ship for some reason. I just went back and double checked, and while a cool idea I realised that the problem is that once I get damaged I can't work out how to use the repair mechanic.
I think the colours chosen are pleasing, and I like that you used the three colours to create a gradient background. At first, I thought you hadn't obeyed the constraint at all but then I was really impressed because it is such a clever way of implying extra colours without using other colours.
Thank you! Super cool.