In this talk, Jamie will demonstrate how to use Kotlin in TeamCity to go beyond the limitations of traditional YAML or XML build pipelines. Starting with a simple single-file build script, he'll show how to develop it into a cleaner, multi-file structure that's easier to read and maintain. The session will also cover how to use inheritance to create custom, reusable Build Types, reduce code duplication, and leverage Kotlin language features to increase developer efficiency. These techniques will be illustrated using a multi-OS Unity project that requires running both Edit Mode and Play Mode tests.