You could have downloaded gnuboy 1.0 for Mac from our application library for free. Gnuboy for Mac lies within Games, more precisely Tools. This free Mac application was originally designed by Mac EmuScene.
From the developer:
gnuboy is a MacOS X compatible Gameboy emulator, that allows you to play Gameboy games on your Mac.
You may want to check out more Mac applications, such as zeroN64, which might be similar to gnuboy.