# External language runtime integration [Back to External process languages](https://rustic-game-engine.pages.dev/markdown/guides/gameplay-programming/external-process-languages.md). Every supported gameplay language calls the engine-owned API. SDKs are supplied by Rustic during validation/build and at runtime; generated editor copies live in `.rustic/generated/programming`. Gameplay scripts do not implement a JSON request loop, build response commands, or serialize output. Existing custom protocol programs remain compatible, but new scripts should use the native API. Lua and JavaScript use embedded bindings. Python, C#, C, C++, Java, PHP, and Luau use persistent isolated sessions. The engine supplies each callback's owner state, input, properties, attributes and scene references. External mutations apply after the callback in issue order. Luau returns a behavior table and keeps its typed locals alive across callbacks; its engine-owned Luau host handles invocation. CSS alone is styling; HTML inline JavaScript has the JavaScript API.