I recently have gotten quite into the game and would love to know if there are others on this small site that share my interest. Honestly, I am likely one of the first to post about this game here. osu! (yes, that is how it is spelled) is a rhythm game consisting of 4 game modes, the most popular being called osu!standard. osu!standard involves clicking circles and sliders to the beat of the music. It is a very interesting game, for the high-skill players are so far removed from the beginners.
The mode I play the most on this game is osu!catch. It involves controlling a character collecting fruit to the beat of the music.
It is a highly competitive game with millions of players. For no reason in particular, the game attracts many people who are into anime, so a large number the most popular maps will be anime related. It does not have to be that way, however, as it is simply a rhythm game.