Mednafen is a portable, utilizing OpenGL and SDL, argument(command-
line)-driven multi-system emulator. Mednafen has the ability to remap
hotkey functions and virtual system inputs to a keyboard, a joystick,
or both simultaneously. Save states are supported, as is real-time
game rewinding. Screen snapshots may be taken, in the PNG file format,
at the press of a button. Mednafen can record audiovisual movies in
the QuickTime file format, with several different lossless codecs
supported.

The following systems are supported(refer to the emulation module
documentation for more details):

Apple II/II+
Atari Lynx
Neo Geo Pocket (Color)
WonderSwan
GameBoy (Color)
GameBoy Advance
Nintendo Entertainment System
Super Nintendo Entertainment System/Super Famicom
Virtual Boy
PC Engine/TurboGrafx 16 (CD)
SuperGrafx
PC-FX
Sega Game Gear
Sega Genesis/Megadrive
Sega Master System
Sega Saturn (64-bit only)
Sony PlayStation
Mednafen is distributed under the terms of the GNU GPLv2.

Due to the threaded model of emulation used in Mednafen, and
limitations of SDL, a joystick is preferred over a keyboard to play
games, as the joystick will have slightly less latency, although the
latency differences may not be perceptible to most people.

Compatibility
Architecture: x86 (Intel:Mac)

Intel Mac OS X 10.5.8 and later