Emulater's...

A video game console emulator is a type of emulator that allows a computing device, usually a personal computer, but also other video game consolesand mobile devices running operating systems such as Android to emulate a video game console's hardware and behavior and play games for that platform. Emulators are most often used to play older video games on personal computers and video game consoles, but they are also used to play games translated into other languages or to modify (or hack) existing games. More often than not, emulators offer additional features above and beyond that of the original console, such as multi-controller compatibility (such as PlayStation controllers being used with Nintendo 64 games and vice versa), timescale control, higher framerates, higher resolutions, unlocking of gameplay features, memory modifications (like GameShark), and one-click cheat codes. Emulators are also a useful tool in the development process of home-brew demos and the creation of new games for older or discontinued consoles.

Emulater program for Mac OS X:

OpenEmu

For the first time, the 'It just works' philosophy now extends to open source video game emulation on the Mac. With OpenEmu, it is extremely easy to add, browse, organize and with a compatible gamepad, play those favorite games (ROMs) you already own.

Download and read more on OpenEMu's Website...