Please tell me if I am in the wrong category. When I develop Roblox, I love story games. They are one of the best types of games I love, but one of my least favorite things is the lack of combat story games. What do I mean by combat story games? Combat story games are where instead of going through tasks and things you have to survive, you instead have weapons of some kind, and you oof enemies and defeat waves of enemies to finish your objective. A great example of this game is Infection - Roblox by SamsungXVI, the creator of camping. The game requires 10 players to play so you may want to search up a video about it. Anyway, the thing I loved about that game is there was a lot of excitement and action in this game. There were also some great features I loved about this game. For example, there are some classes that you can choose and play as. There are many locations or chapters that have their own challenges. This game is really amazing, but there aren’t any popular combat story games anymore. They are pretty much dead. Which is why I want to make one. Now before I get into the questions, this game is NOT going to be used for gaining Robux, getting fame, or any stuff like that. I want to make this project for fun and create it especially for experience. I have come to ask you what should I first start with? What should I learn to be able to make the things I want. Now again, make sure to look at infection or this other game Defenders Of Roblox! - Roblox. Defenders of roblox is a old game in which lots of their scripts are outdated and the game is basically broken, but there are links to videos in the games description. Remember this is for experience and for fun. I am also a young developer so don’t expect me to have proper grammar or totally understand everything.
This is the right category. I recommend splitting your posts into sections like paragraphs, though, bit confusing to read.
I would start learning basic combat mechanics, swords, pistols, etc. and also basic NPC artificial intelligence - zombies targeting players, making paths around walls. And then move on to advanced mechanics of combat and AI.
Then after that you’ve got the base game ^, you can work off of that and like you mentioned create classes, chapters, challenges which I would begin by learning basic GUI uses, e.g. how to assign values to a player who has pressed a button, so you can for example determine if they pushed A or B, and give them the corresponding item.
One thing I have learnt through experience - Don’t make building the focus of the game. Start with the mechanics first, or you will spend a lot of time making a house or something but no enemies. Builds should always be last in the list for a game that relies mainly on mechanics.
This doesn’t mean rush the builds - just don’t lose focus.
Hopefully that was easy to understand. Reply if you need me to clarify something, and good luck making the game 
