Visual wise it is very good, the arm following the player are adding a lot of charm to the game.
I do think there is no audio wich is a shame but 30 days can only get us so far so it is normal.
Now for gameplay: tldr: Very fun but very unforgiving
1- The blue comets comes way to fast I think
2- overall the comets are very fast maybe it could have been better to have the speed ramp up over time
3- the big comets are perfect, we have time to see them and create a strategy on when to break them. Breaking them takes a bit of time but not too much, it feels great to break them
4- the movement is really good, jumping feels very good
5- The biggest problem of the game, the detection box for breaking the comets is way to small. For the big ones it is not a problem and for the normal ones it is ok but for the blue comets if is very annoying to visibly be on top of them but pressing the button like a frame too late and not break them. I don't know how big it really is but is should be quite a bit bigger than the character I think.
Overall fun game !