Socol is a mix of "color-matching" gameplay with sound/music. The player rotates a colored ring catching glowing orbs which emit from the middle.
To rotate the ring, click and drag left or right with your mouse, or press the left and right arrow keys. Select "How to play" in the main menu for further instructions.
A context menu should be shown when right-clicking or, on touch devices, long-pressing in the game. This menu especially allows to play in full screen and control the volume.