For the past months I've been studying programming and I've finally learned how to code, but one thing that is confusing me is how to properly organize the design of a game project - code wise.

The game I'm building is a pretty standard commercial game. It has the basic components of a normal game: A world, characters and items interacting with each other and all of this is run by game manager. Basically you play as a hero in a world and do stuff. Fight, explore and interact.

Think of your standard adventure game that starts off with an intro, goes to the menu system, then gets into the game and back to the menu. Pretty much like 99% of any commercial game or otherwise serious game projects. Thats what I'm aiming at.

The problem is:

How do you properly code a commercial game architecture?

How do you organize it?

How do you make it not become unmaintainable spaghetti code?

What specific things to keep in mind when building this, codewise?

How you can help me:

a) Please tell how do you code your own game projects. What is your thought-process when designing the architecture?

b) Recommend books, blogs, tutorials, videos or anything else on how to organize a commercial video game.

c) Give hints and tips on do's/don'ts when building a game, codewise.

Please help!