In order for you to play Warhammer 40,000: Dawn of War II - Retribution - The Last Stand on macOS with minimal graphics settings, your computer must meet the following requirements
Operating System:
10.10.5
Processor (CPU):
2.0GHz Intel or greater
Memory (RAM):
4GB
Graphics Card:
512Mb AMD 4850, 512Mb Nvidia GT130, Intel HD4000 (See Notes for more details)
Storage:
8GB HD space