In order for you to play ShellShock Live on macOS with minimal graphics settings, your computer must meet the following requirements
Operating System:
Mac OS X 10.7 or above
Processor (CPU):
Intel Core 2 Duo or above
Memory (RAM):
1 GB RAM
Graphics Card:
Shader model 2.0 capabilities; generally everything made since 2004 should work
Network:
Broadband Internet connection
Storage:
500 MB available space