Apple Arcade games could be played in the future by using console-like game controllers that magnetically snap on to the sides of an iPhone or iPad.
Mockup of adding a game controller to an iPhone
Mockup of adding a game controller to an iPhone
Plenty of Apple Arcade games are either made to be played with a game controller, or just work better with one. Currently your best option is to just buy a separate controller, although there are products such as the Backbone One.
That $99 device takes the left and right side of a familiar-looking game controller, and separates them with a wide, flat stretch of plastic. It’s exactly the right size to slot an iPhone in, and the result is a regular iPhone with full game controller paddles and buttons.