Gg! You know your limitations and where to improve, there's not much to add.
If you were going to make one update and then drop it forever... Yeah, the sprites and colors. I'm not colorblind (I think?) but the magenta and red are egregiously similar, the blue and teal, the green and uhh seafoam? The shape needs to get very different when they're on the same quadrant of the color wheel.
Then add a shotgun, idk. :)