The first thing you probably need to start with (I do not take into account the game itself)) is mod building.
Mod (short for “modification”, game modding) is an add-on to a computer game, usually written by third-party developers or amateurs using the SDK, attached to the game or special amateur programs developed for modifying games. Mods are usually developed by fans and for fans and are supposed to be distributed exclusively free of charge. Unlike add-ons, they often change the balance of power (in strategy games) or the set of weapons and capabilities of the hero (in 3D shooters).
Modding will allow you to understand the internal logic of your favorite game, how it works and what can be changed in it for the better (and sometimes for the worse).
The second thing is to correctly formulate your goals in the development of computer games. That is, ask yourself a number of questions: create mobile applications or browser games, do game development professionally, or devote your free time from work? You also need to understand what you prefer: creating an interface, creating gameplay or writing scripts? Or maybe you want to be a 3D artist? Setting your goal correctly will put you on the right track.
And, of course, you formulate a number of questions – what you need to know. I will provide examples for writing game scripts, logic, behavior, etc. That is, programming (this is what I do).
Question number one: which programming languages for games to choose? Honestly, any will do (only compiled languages, such as C ++, C #, Java, Objective C, etc.), the main thing is that a novice developer, for example, who knows the basics of C # programming, understands the principles of developing not specifically games, but the basics of programming logic (that is, the future of logic in game development).