Welcome back! Maybe you have heard about the Event System in Unity. Maybe you have already used it in UI like this: The Event System does not have much functionality exposed, this is because the Event System itself is designed as a manager and facilitator

The Event System consists of a few components that work together to send events. When you add an Event System component to a GameObject The fundamental object in Unity scenes, which can represent characters, props, scenery, cameras, waypoints, and more.

Make sure to unsubscribe these events as they may lead you to some unwanted errors. For example, if you destroy your door at runtime, etc. So, that’s how we can make our simple event system.