MAME stands for Multiple Arcade Machine Emulator. When used in conjunction with images of the original arcade game's ROM and disk data, MAME attempts to reproduce that game as faithfully as possible on a more modern general-purpose computer. MAME can currently emulate several thousand different classic arcade video games from the late 1970s through the modern era.
The source code to MAME is available for development and learning purposes. Most of it is free and open source.
The main purpose of MAME is to be a reference to the inner workings of the emulated arcade machines. This is done both for educational purposes and for preservation purposes, in order to prevent many historical games from disappearing forever once the hardware they run on stops working. Of course, in order to preserve the games and demonstrate that the emulated behavior matches the original, you must also be able to actually play the games. This is considered a nice side effect, and is not MAME's primary focus.
There is frequently updated SDLMame version for Mac OS X. You can download it from here. You will need some GUI.
MAME OS X is a native version of MAME with built in GUI but badly outdated. You can download it from here.
There is even older build of MacMAME that You can find on MacMAME homepage.
There are several GUIs for MAME that You can use:
- QMC2 is the successor of one of the first UNIX M.A.M.E. GUI front ends available on this planet called QMamecat. It's working very well on OS X and you can find it here.
- There is also a mac build of M+GUI that I didn't test. You can download it from here.
- Attract-Mode is a GUI for emulators such as MAME, MESS and Nestopia. It hides the OS and is intended to be controlled with a joystick, gamepad or spin dial. You can download it here.