If the specs didn't convince you that this is a gaming system, perhaps the special ‘Alienware Gaming Services’ will. It's a service designed solely for helping you optimise games.
The Alienware X51 R2 comes with gaming peripherals such as an optical mouse and a multimedia keyboard from Alienware. Those look like gaming products, but the mouse is a bit on the light side and doesn't have any extra gaming functions. The keyboard is of a higher level of quality. It has a good keystroke for a standard keyboard, even if it doesn't gave lots of extra features. For some strange reason it's not possible to order Alienware's own (and better) gaming accessories when you order the X51 R2.