This was a nice relaxing game! The visuals are great and I liked the glow effect. I also really liked how the asteroids would play a different tone when you picked them up so they kind of formed a small melody.
Some ideas for improvements to the graphics / UI:
- Maybe consider some faint glow to the background or a subtle gradient? You already have a little of bit of variation with the stars being different shades of gray and some variation to the purple would be nice too.
- A small score counter on screen would improve the game-aspect of it and help you get a sense of progress I think.
- It looks like it was a style decision to do no-filter and pixel perfect rendering? I think leaving the inside of the planets pixelated is nice but it might work well with the glow to do some antialiasing on the border of each planet so that the outside of the planet looks a bit smooth but you still get the pixel art effect.