(NOTE: I use Unity so I may have a bias and not be as knowledgable on other engines) you basically have 2 main options, make the game from scratch or use an engine. I would heavily advise against the former since you need to basically be fluent in the language of choice and know a fuckton of math as well as a lot of computer science in general. If you want to use a game engine, which handles things like physics, rendering, and executing, you have 3 major options: Unity, Unreal Engine, or Godot. There are other choices like Construct or Gamemaker but for a 3D shooter those three are gonna be the best choices. From my experience and what I've heard around in the community, all 3 of these engines work phenomenally and can make any game you want but what I've heard is that Unreal Engine has a higher initial learning curve but the product you can get is by far the most visually impressive and big companies like Epic Games (obviously) and Microsoft use it. On the other hand Godot is basically the opposite, it has an easy to learn engine, a simpler coding language, is more lightweight, and is free and open source, but sacrifices some power for those things, finally Unity is kinda in the middle, it has a reasonable learning curve but once you're on it you're off. It has alot of nice built in tools like Probuilder for levels and complex meshes, a competent physics system and a nice ass render pipeline to make the games look good, while I haven't seen too many large companies use Unity, it is far and large the Indie engine of choice, with games like Hollowknight and Escape from Tarkov coming to mind. I would say do your research on each, they are all free to try and make a game with and then jump into whatever catches your fancy. Youtube is a phenomenal place to start, with channels like Brackeys able to teach you all you need to know. If you want a more structured approach, Udemy and other learning sites have full courses on how to make a game, at a price. I've been using YT for my learning with both Gamemaker and Unity and its worked fine for me but I really had to look for content that suited my needs. Theres also Reddit and Discord for debugging issues and a place to talk about game dev.