Mac: Some Mac games have gamepad and joystick controls functional out of the box. Some don't. For the latter, a little app called Joystick Mapper can allow you to use any compatible controller with any game -- whether it supports your gamepad/joystick or not.
All you need is a connected joystick or gamepad to get started -- you can even work with an Xbox 360 controller. From there, you can create a new joystick and select it in the app's settings. Once you've done that, you simply bind buttons on your device to keyboard strokes and mouse actions to control whatever game you want in the way you want to control it. That allows you to use your controllers with older games that don't have the proper support or newer ones that just left it out for your controller of choice.
It might take a little bit of work, but the setup is minimal. For $5.49, you get an app that will let you control your games with a joystick or controller in virtually any way you'd like.
Joystick Mapper ($5.49) [Mac App Store]