This chapter enters the world of Mecanim animation by explaining in depth how to create an interactive scene, complete with movable objects. Specifically, we'll create a scene where the player (in first-person mode) can press a button or lever to open a door elsewhere. This simple scenario will feature interactivity (the player presses a button), and in response, a door animation will play (a door rotates on its hinges in response to the button press). By creating this project, we'll explore the Mecanim animation system in Unity and see how to create interactivity without any traditional scripting. Let's jump in and get started.