This is probably going to be more of a question about how OOP languages and procedural languages are used to design a game.
Most tutorials and pages I've seen that are using an OOP language (eg. C++ or Java) use objects to create basically everything used in the game, for example a class for the user controllable character, a class for bullets on screen, a class for smoke effects, another class for a flying arrow etc.
My first question is this: Is the idea of implementing everything in the game as a class a "normal" or "recommended" idea to adopt? Is this how I should write my game if I'm using a OOP language?
My second question is this: If someone was to write a game in a procedural language such as C, how would you go about creating the same system? I can't create an object for each in game item. Presumably, I would create a struct and have an array of said structs? Also, with a OOP design I would have each object being able to control itself (eg. collision detection). How would I achieve this in a procedural language? Have some kind of code which iterates through each struct and manipulates each struct from there?
Regarding your first question: This is just how things come along the natural way. When you think about your game, you will think about the player, enemies, scenes, rooms, weapons, objectives etc. pp. - all those things are naturally modeled as objects in the sense that they group properties (i.e. member variables) and behavior (i.e. methods). So that is just the way it usually is, and if the language that you choose to implement that stuff provides a way to express this, why would you not use it?
Regarding your second question: if the language of your choice does not allow a close to natural implementation, you will want to try to model it as closely as possible to that. To pick up your example: you would model your objects with structs (properties) and implement behavior accordingly - either with functions operating on those structs (e.g. enemy_hit(player)) or with function pointers contained in the structs (i.e. player->hit(player,...)).