In this game a priori easy of skill and logic, avoid to your circles from striking the moving triangles and other circles. The problem is that at each level, a new circle appears and makes the task much more complicated!
Simple but daunting!
Move the circles with the mouse.
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.