Hmmm
A little exposition would have been nice.
Sure shooters aren't super complex, but how about giving me just the slightest bit of instructions? You told me to switch colors by clicking: that's it. You didn't explain what I was shooting for, leveling up, combos, when and why I lose combos, death, if missing enemies has any negative consequence, if colors affect hitting bullets or not, and whether I have a health system or if it's just time and time alone. All these things would have been nice to know even if you thought they were obvious: because they weren't.
Seriously: you explain so little it's almost a joke. It really ruins the fun if you have that "What am I doing? Am I winning?" feeling when playing a game.