How does that work, does it accept Nintindo games or something?
You actually purchase an interface called an iPac. The games are loaded on to a PC. The PC's keyboard actually plugs in to the iPac and the game's buttons are wired in to the other end of the iPac. When you press the buttons and use the joysticks the iPac translates these presses in to keyboard strokes.
I bought a dead arcade cabinet for about $10, gutted it, bondo, sanded, painted, new T-molding, caster wheels, sanded and painted the coin door, installed collapsable drink holders on side, etc. Mounted the PC speakers with accessible volume control. Put together a custom marquee with backlighting. The overlay on the control panel is a checker pattern of Captain America Comics #1-50.
Mine was setup with the standard Street Fighter 6-button setup so that I could play pretty much any game. Some people go crazy with these things setting up rotating panels with different kinds of controls on each side (joystick/buttons, roller ball, steering wheels, etc.)
Had ALOT of fun with this cabinet. Sold it a while back but will be building another in a few years when my oldest can appreciate it.