I want to develop a game and make it a hassle free experience for other developers to make mods for it.However, I don't want to open source my game because I would like to sell it.My idea was to create a kind of API that others could hook into to add and modify content in the game. The idea would be similar to a frontend using a REST API to interact with the backend.I wonder if there are best practices when it comes to making your game modable. How is it usually done by professionnal game devs?