Valve have teamed up with nVidia to try and promote using their hardware with the service, and have given users an incentive to download and sign up for a Steam account; a free extended demo of the absolutely stunning, game of the year winning puzzling PC game, Portal.

If you have a nVidia graphics card, head on over to Steam and sign up for an account to get yourself a free slice of Portal, and remember: The cake is a lie!