• You must first go to settings, then graphic options, and then windowed mode. If it's lit up, it's about to be minimised. If it is minimised, you can do anything you normally can on your computer, but if you open Safari, for example, the game will be paused. It will be full screen if it isn't lit up, and you won't be able to do anything else but aoe3. However, the graphics are excellent in full screen.
• The following are the recommended minimum requirements for Age of Empires III Definitive Edition on a Mac: Processor: Intel Core i5, i7, or i9 processor
• 16 GB of memory or more
• SSD disc for storage
• AMD graphics card is used for graphics.

Read More: What is bad about Mac OS?