It's a very simple game at first glance. Every round, the walls close in, and you need to use your mouse to place the sphere in a safe area before the walls close. Every 5 rounds, the speed of the walls and the size of the sphere increase. That's it. Sometimes, there may not be a safe area, but it's not a problem, and you don't have to place the spheres all the time. Instead, the round will be restarted, and the game will continue without interruption.