Old school gaming fans on the Mac have a new tool to add to their arsenal thanks to the efforts of OpenEmu's developers. It emulates several older game systems and handhelds, according to Cult of Mac.
The software supports game controllers and provides a unified interface to keep track of the ROM files you've downloaded. While we certainly don't condone game piracy, you can make a case for playing ROM files for games you've purchased legally and still own, and for an old-school gamer like me, that means playing classics like Super Mario Bros. and Sonic the Hedgehog.
Game ROM files are displayed with their original box art, much like album art in iTunes. And the best part of OpenEmu is the depth and breadth of emulation it can manage: vintage 8-bit and 16-bit Nintendo and Sega home consoles and handheld gaming systems are well-represented, along with TurboGrafx-16 and NeoGeo Pocket.
OpenEmu operates using several different open-source emulation cores, and keep tracks of game ROMs for each system in an independent list that appears on a sidebar. You drag and drop ROM files into OpenEmu to add and run them.
If you're not sure where to download ROM files from, OpenEmu offers a starter pack of homebrew games you can download to get started.
Source: Cult of Mac