Hi, in general it is a good start from my point of view, although there are many things that I could "criticize" (I will not say them since they are mostly things that if you continue to develop it they will improve with each update, so it is not necessary mention them).
| To help, I may suggest adjusting the bottom of the beatmaps selection menu as it appears to be somewhat "incomplete" or "not level" with the back button.
| I would also recommend that when you get an "A" rating, this letter is the same size as the rest of the rating letters (based on what I can see in the screenshots).
These are for me, the main observations that should improve.
| Remember that everything can always improve! So that you can have better results, keep developing it!