Seriously, robots. Stop falling down caves and having adventures already. Thinking you're all cool with your platforming and gem collecting, all strutting around using the arrow keys and jumping by pressing X.
Arrow keys = Move. X key = Jump. P = Pause. Click on "menu" = back to main menu.
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.