so basically what is osu?
osu! is a rhythm clicking thing which can play on pc.
It can also play on android or ios platform.
so what's this thing all about?
osu! want you to click "o" thing with "1,2,3..." on it.
not only that, osu! also want you to hold that "ball-rolling-thingy".
and osu! want you to spin tornado too.
so what about that rhythm part?
osu! wants you to click all "o", hold "ball-rolling-thingy" and spin tornado by following rhythm.
osu! is hard actually. Good luck with it!