Bubble Bobble

In a Finite State Machine each state is represented with a class. The Player- or EnemyComponent checks whether the current state returns another state.

Each state is provided with a OnExit and OnEnter method. Handy to e.g. (un)register certain inputs per state. (Alternatively, you could use the constructor/destructor)

I decided to let the state decide what animation should be played. I created a struct that saves certain sprite data. I let each state own an object of this sprite data to send that data over to the SpriteComponent. 

I use Pushdown Automaton (stack-based state machine) for handling the scenes. The scenes are handled like states and get pushed on, popped from or set on the stack. This stack-based approach is especially handy for moments where you want to still render the previous scene in the background while processing the current scene.
E.g. pause-screen, dialogue pop-up, etc...
The scenes in the background become suspended and don't update anymore until you pop the current scene from the stack.

To showcase the flexibility of the engine, I made a Versus mode where player 2 plays as an Enemy.
Just by adding the movement component to the enemy object (like you would do for the player), the player is now able to control the enemy.
The MovementComponent creates the necessary input commands and provides public functions to (un)register those commands to the Input Manager.

This in combination with the state machines, makes it extremely easy to enable/disable certain inputs for certain states.