error CS0201

error CS0201: Only assignment, call, increment, decrement, and new object expressions can be used as a statement

it only happens when i put this

public void ExitOn()
{
	Application.Quit;
}

@Tritekstyn

It needs to be

Application.Quit();

Not

Application.Quit;    

You should try this out

// public function to remove player life and reset game accordingly
public void ExitOn()
{
    #if UNITY_EDITOR
        // Application.Quit() does not work in the editor so
        // UnityEditor.EditorApplication.isPlaying need to be set to false to end the game
        UnityEditor.EditorApplication.isPlaying = false;
    #else
        Application.Quit();
    #endif
}