Crashes on each mission

Love the call of duty game(s) but this one I bought in the Apple App store yesterday for MAC OSX is always crashing/freezing mid-mission(s). Please fix the crash/freeze issue! I have the 21.5 retina iMac, 3.1Ghz, intel iris pro 6200, 8GB memory late 2015 model, OS X 10.11.4.

Davidsbmw about Call of Duty®: Black Ops