In order for you to play Britannia on macOS with minimal graphics settings, your computer must meet the following requirements
Operating System:
10.13 or higher
Processor (CPU):
2.5 GHz Intel Dual Core
Memory (RAM):
2 GB RAM
Graphics Card:
Metal supporting graphic card (2012 latest)
Storage:
750 MB available space
In order to play Britannia on macOS with maximum graphics settings, you need a computer with a configuration no worse than the following
Operating System:
Sierra 10.13 or higher
Processor (CPU):
2.5 GHz Intel Dual Core Or Apple Silicon ARM
Memory (RAM):
4 GB RAM
Graphics Card:
Metal supporting graphic card (2012 latest)
Storage:
2 GB available space