I'd bet that porting games that survived the transition to Catalina (and many, many did not) will be pretty easy. I guess if I had to bet, I'd bet that if anybody actually uses hand tweaked assembler, it would be the people who develop engines (like Unity or Unreal), and that most developers are using higher level tools. In fact, I'd bet the transition to ARM will be easier than the transition to Catalina (I still haven't upgraded to Catalina because I'm not ready to give up some older games) Stated differently - to what extent do game developers use languages and APIs that are high-level enough that porting will be easy, versus using hand tweaked x86 assembler that would make porting hard? But is that true? And how easy/hard is it to port the engines? Some are already on iOS, but how much does that help? A free and open-source application that emulates the original Microsoft Xbox game console, enabling people to play their original Xbox games on Windows, macOS. I could imagine that once popular game engines are ported, it might be relatively easy to port the games that use those engines. I'd love to hear from game developers regarding the potential ease or difficulty of porting games from Intel to ARM.

Play emulator games on my mac