I know that running Unreal Engine is slow on a Macbook Air. But if you were to create a game on a desktop computer, then package it for Mac, could a Macbook Air run the game smoothly?
If the Macbook Air meets the system requirements and the resolution and quality settings are set low enough…then yes.
Note the “OpenGL 4.1 compatible graphics card” – not sure whether any Macbook Air models meet that requirement or not.