There is no one definitive way to code a game app, as the process can vary greatly depending on the type of game and the platform it is being developed for. However, in general, game developers will use a variety of programming languages and tools to create the game's codebase, which is essentially the foundation upon which all other game features are built. This codebase will include both the engine code that powers the game and the various scripts and assets that make up its gameplay.