Finally managed to get the game running on my iMac late 2012, however it freezes/crashes immediately in the tutorial when encountering the 2 assassins in the hallway (the first assassin works fine).
I know late 2012 iMac is on the lower end, I had to set graphics to low in order to make animations smooth. Running OS x El Capitan at the moment, iMac is generic 2012 with 8 GB RAM upgrade, using borderless as is the default. Is it likely my underwhelming computer causing the crash or could something else be done like upgrading OS X or running Boot Camp instead on the same computer? Anything else?