In order for you to play Monaco: What's Yours Is Mine on macOS with minimal graphics settings, your computer must meet the following requirements
Operating System:
OS X version Snow Leopard 10.6.3, or later.
Processor (CPU):
2.0+ GHz
Memory (RAM):
2 GB RAM
Graphics Card:
OpenGL 2.1 and shader model 3 with 512 MB of memory.
Hard Drive:
500 MB HD space
Additional:
Not recommended for Intel integrated graphics, Mac Mini's, or early generation MacBooks
Online:
Steamworks required for online play, LAN not supported on Mac