Acorn Factory is a physics simulation game. Your job is to send acorns to the goal using different machines, such as pushers and rotators. Click on their red buttons to activate them. By the way, why don't you create your own levels and share them with the world with the built-in level editor?
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.