McOsu is developed separately from and has no direct affiliation with osu! or ppy Pty Ltd.
McOsu is NOT osu!
Now with Virtual Reality Support!
A free open-source circle-clicking rhythm game client for osu! beatmaps, with the main focus on making practicing easier and customizing gameplay.
It is primarily a practice client for getting better at the official game by having tools at your disposal that osu! doesn't provide for some reason, it's not supposed to be a perfect copy of osu!, or to otherwise profit with a free game from a free game (what)!
If you have never played osu! before, then I do not recommend using this client (except for VR players of course), as there are no gameplay tutorials in here (just google "osu!" and play the official game which is a lot more polished).