There are many alternatives to Mame for Mac if you are looking for a replacement. The best Mac alternative is RetroArch, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 10 alternatives to Mame and four of them are available for Mac so hopefully you can find a suitable replacement. Other interesting Mac alternatives to Mame are OpenEmu (Free, Open Source), Nostlan (Free, Open Source) and SDLMAME / MESS (Free Personal).
What is RetroArch? RetroArch is a modular multi-system emulator system that is designed to be fast, lightweight, and portable. It has features lacking in some emulators frontends, such as real-time rewinding and game-aware shading. What systems does it play?
Open Emu is an open source project to bring game emulation to OS X as a first class citizen, leveraging modern OS X technologies such as Cocoa, Core Animation and Quartz, and 3rd party libraries like Sparkle for auto-updating.
A front-end or user interface (UI) is the presentation and interaction layer of an app or website. Most modern emulator apps have basic game list UIs that you can interact with using a mouse/keyboard but not a game controller.