Most of what you already have looks extremely good.

Some suggestions that might make the skin better:
- more icons/colours for the different mods
- have the input overlay keys press into some sort of intricate sci-fi console
- make the solid border of the hit circles smoothly transition to the inside somehow. One way of doing this:

(there are probably better ways of doing this but I can't think of them atm)
(or maybe remove the solid border altogether, and make it more like the circle that covers osu! logo in the song select)
- the pause menu could have something that says "paused", maybe with that alien font you used for "combo" and "accuracy" on the ranking screen
- the playfield could have some reference points or something that lets players know where the play square is. For example:


hope this helps

Released the skin for public test

POG