Any project of a sufficient size and complexity is going to run into issues related to managing your game objects as and when they are added and removed from a scene. If you don't get your design right from the start, you are setting yourself up for a world of mess later. A common way to handle this is to use one of the three patterns, single instance managers, singletons, or a dependency system, to manage these controllers for you.

There are two main ways through which you can implement the singleton pattern in Unity. The first way is to use a public static parameter within a class to maintain the runtime class. This also allows any other script to access it from anywhere in the game and is useful if you want other...