Guilty Gear (PSone, PS2, Xbox, GBA, DS, Wii)
Guilty Gear first appeared in 1998, so it's almost ten years old. But it hasn't really changed much in that time. In fact, its updates seem even less visibly different than another similar game on this list. Sure, the combo system's been improved and it's now online-enabled where before it wasn't... but that's about it. We like to think there's an original version somewhere in a heavy metal bar, still being played by some grizzled old biker dude clad in leathers who always plays it when he rolls into town.
Above: The graphics have improved but not really changed. And... anyone?