Factorio is a great example of a game that benefits from having a custom engine. For comparison, Cities Skylines (Unity) becomes CPU bottlenecked with a large e

Factorio is a great example of a game that benefits from having a custom engine. For comparison, Cities Skylines (Unity) becomes CPU bottlenecked with a large enough population. Making large cities practically unplayable even on the most powerful consumer CPUs. Also, choice of programming language isn’t what makes porting games difficult. It’s the platform specific graphics, input, window management, sound, etc. All of which aren’t handled by switching to one of the languages you mentioned.