The idea is quite common. You are going to catch the rhythm of the song by clicking on the prompts with the mouse in time. They look like big multi-colored numbered circles, so it’s quite difficult to get lost in the action.
Note that the music tracks are built by the users themselves. You can make a track for OSU to your favorite song. You can choose any track you like to follow the tapping aim.
There is multiplayer here, and this part is incredibly fun. You can compete with your friends on the quality of hearing and the ability to quickly respond.