Basilisk II is an open source, 68k Mac. emulator.
It enables you to run 68k MacOS software on your computer, even if you are using a different operating system (however, you do need a copy of the MacOS and a Macintosh ROM image to use it).
The Official Basilisk II Home Page
<RIGHT> MacOS X (native windowing) port
by Nigel Pearson <nigel@ind.tansu.com.au>
SDL2 port
by David Ludwig <dludwig@pobox.com> </RIGHT>