Osu! Is one of the greatest rhytm games to ever exist, being fun for almost any skill level and sorting an infinite amount of songs, especially if you're into anime, but the truth is you can find almost anything here, even if it's a crappy beatmap with unbalanced difficulty.

The skill ceiling is endlessly high and the community is alive and welcoming for what I can say in my experience.
The multiplayer modes lack an individual difficulty selection, but I understand they are more meant to be a "competitive" mode rather than a Fortnite Festival-like "play a song with your friends".