I like the simplicity in art style and the relaxing music to go along with it. The leveling progression is nice. the available options to mute sounds is good.
one thing I noticed when playing is that I only focus on the strength meter on the left and try to time the press to be perfectly between the min max and usually get a bullseye or close every time. So I ignore the board all together which is rotating back and forth and has lots of information, until after the press is when I look to see what i got.
I also quickly noticed is that depending on the strength meter press the dart is only thrown on the horizontal axis left or right, which I think can be improved by changing it to the vertical axis , when we play darts irl we think about the arch in our throw with gravity being a factor. So shooting the darts in the vertical axis would imo feel similar to the real deal and be an improvement.
A thing you could also try is color indicate the strength meter ( red = max strength ) ( lime green = perfect timing ) like a lot of games have or a gradient in the meter would also be a good thing to try.
Sound effects for both perfect star shots and skull hits would also be a nice addition I think adding a little more juice to your game.
over all I think you’ve made a nice game. cheers~