Well done so far. You have added basic functionality like jumping, physics, and running to the PlayerController object. We are definitely going in the right direction here. The next important step is writing a neat GameManager class to help us control the game events like:

For basic games like Jake on the mysterious planet, it is a good practice to have one instance of the GameManager running and controlling all main events in the game. The gameplay loop is simply a journey from the gameplay start to the gameplay phase and the game over phase. Time to write some code!

Let's create a new C# script and call it GameManager, and write the following code:

As you can see, nothing is very complicated. We wrote very simple methods to help us control the main game events. This script does nothing yet; however, please add it to the Unity Scene. Create a new game object call it GameManager, and add the GameManager component to it. We will use it in the future.

We won't test this code in Unity yet. Let's think what can be improved. Would it be nice to have only one method to control the main events in the game? Let's edit the code a little to have something like that.

We have an enum GameState declaration in lines 4 to 8. What is enum? If you check on Google, you will be probably be directed to the Microsoft documentation. From the C# documentation:

Yes, this is a massively overcomplicated definition. Let's forget it and make our own, simple one by defining what we can use enum for.

Enum is a set of magic constants you can control your code with. We can define few states stored in enum and use it without risk of typos like with using the string. Lines 4 to 8 simply create a new enum, which works like an object and can be passed to the method as a parameter. The rest of the code should be well easy for you to understand. SetGameState is called with a certain GameState enum value. Note that we are also storing the currentGameState value for the future.

We have more code that allows us to control events in the game. Now, we need to make some real use of it. If you press Play in Unity, you will see that nothing has really changed. Jake still runs the same way he did before GameManager was added. This is because nothing actually changed in the PlayerController class. PlayerController and GameManager are two separate instances of two different classes. They won't affect each other's behavior until we write some additional code.

We have already seen how to access components from different scripts by creating public member variable and dragging the game object to the field in Inspector. It is a good approach for this situation. However, I want to show you something better. If there is only one instance of the object required in the project, we can use the singleton approach.