My background is backend development with Java and Kotlin for the last decade. I have a little bit of HTML/JS experience but I’m not a pro. I would like to build a modern Sierra game, of sorts.
I have no problem investing the time, it just seems overwhelming to jump into and while I’ve looked at a couple of tutorials, I still seem a bit mystified by the process.
I’m interested in multiplayer design and function twofold, as I’m intrigued at both how to make it work efficiently and the reasons some game companies claim their game servers cost millions a month to run and have to shut them off (looking at you, Gun Media).
This is a very common question, I’m sure you can find many articles or videos about “how do I start” when getting into game dev with an engine. As you already have a development background the best way for you is probably to “just build something” using the official documentation only. Pick a “small” game or project as a way to work with the engine and learn how things are done and how all the pieces interact with each other. The more you understand all the bits and pieces and how they are composed together to form a game the easier you will find it to plan and conceptualize your game.
Multiplayer is a super interesting topic, especially regarding these mysterious “game servers” or online services. I recommend Nakama as a FOSS example for one such service - which conveniently also has Godot support. The example project of theirs might also be a good starting point for you to see the engine at work.
Alternatively you can also use your backend experience to build the game services yourself - but that will distract you easily from working on the game itself.