A method comprises linking a plurality of units with a central server, operating a virtual game on the server, and offering purchasing options to users of the units to purchase virtual non-monetary assets for use in the virtual game. Also described is a system comprising a central server, and a plurality of units linked to the server via a communication link, wherein a unit of the system includes purchasing means operable by a user to purchase virtual non-monetary assets for use by a user in the virtual game.