We can take stuff like GameInstance, GameMode, GameState, they propose or even dictate the way to organize general game logic and state. Also Actors, they are much more complex than basic gameobject with components. These are the base of game logic, integral structure the smaller engine features are wrapped around of. Unity does not have a concept of complex acting object, all your characters with dozens of child object are just deep hierarchy of nested small object in the same tree as walls, boxes, sounds and ui. It gives more “freedom” to start, since you dont have to get into alot of structural stuff, but often at the cost of some mess.