In order for you to play Cities: Skylines on macOS with minimal graphics settings, your computer must meet the following requirements
Operating System:
OS X 10.11 (64-bit)
Processor (CPU):
Intel Core 2 Duo, 3.0GHz
Memory (RAM):
6 GB RAM
Graphics Card:
nVIDIA GeForce GTX 260, 512 MB or ATI Radeon HD 5670, 512 MB (Does not support Intel Integrated Graphics Cards)
Network:
Broadband Internet connection
Storage:
4 GB available space
In order to play Cities: Skylines on macOS with maximum graphics settings, you need a computer with a configuration no worse than the following
Operating System:
OS X 10.11 (64-bit)
Processor (CPU):
Intel Core i5-3470, 3.20GHz
Memory (RAM):
8 GB RAM
Graphics Card:
nVIDIA GeForce GTX 660, 2 GB or AMD Radeon HD 7870, 2 GB (Does not support Intel Integrated Graphics Cards)
Network:
Broadband Internet connection
Storage:
4 GB available space