I've just noticed that there is some talk of using the X360-controller, but none about using a common gamepad? (or perhaps I missed it)
I really hope you don't do as all those other games, support everything... but the common gamepads, which is essentially the same as the X360 one, except the X360 doesn't seem to use compatible drivers or access, everyone I know has one, and none of them have a X360-controller.
Some games have run with my gamepad (most common logitech one) as the X360-controller, but with greatly degraded performance and control over axis assignment.