The game throws you in the role of the item shop keeper in a not so fantasy/medieval world.
You role is to gear up the local peasants for them they become warriors (provided a little money), and die happily for the sake of the kingdom (and your shop of course) facing hordes of organised monsters.
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.