The M5StageManager class is responsible for controlling the logic of each stage. We consider things such as the main menu, credits screen, options menu, loading screen, and playable levels to be stages. They contain behaviors that control the flow of the game. Examples of stage behavior include reading game object data from files, spawning units after specific time intervals, or switching between menus and levels.

StageManager is certainly not a standardized name. In other engines, this section of code may be called the game logic engine; however, most of our game logic will be separated into components so this name doesn't fit. No matter what it is called, this class will control which objects need to be created for the current stage, as well as when to switch to the next stage or quit the game altogether.

Even though this uses the name manager instead of engine, it serves as one of the core systems of the game. This class controls the main game loop and manages the collection of user stages. In order to make a game, users must derive at least one class from the base M5Stage class and overload the virtual functions to implement their game logic.