Yeah my game pad doesn't work (Mac) either. Very few games seem to support gamepad on Macs and developers just prefer to shrug it off unfortunately.
The irony is: Unepic, Guacamellee, Hammerwatch, Cave Story +, Megabyte Punch, and several other 2D platformers DO support gamepads on Mac. So a gamepad intensive game, like Valdis Story, not supporting gamepad is unacceptable.
Hammerwatch, Anodyne, Megabyte Punch, Another World (20th AE), Ittle Dew, Teslagrad work perfectly well.
Valdis Story, Unepic, RCR DX, VVVVVV don't recognize my controller.
Don't own Guacamellee and Cave Story.
Sometimes gamepad support is awesome, sometimes it's uneven, (Unepic works for some, but not for me). All in all Mac and Linux gaming have a long way to go. Hopefully our messages don't go unnoticed and developers will see that there is value in supporting these platforms in future.