I've been studying game development for a little over 2 years now, primarily in Unreal Engine. While I've learned quite a bit regarding the "hard" skills of game development (programming, art, animation, etc.), I've really struggled in finding resources that teach the more abstracts of game design. I was wondering if anyone had any suggestions for resources for such things as level design, enemy design, encounter design, etc? There are some great YouTube channels that I've subscribed to, but I feel that most of them are more geared toward deconstructing existing properties and less on the strategies used to create these experiences in the first place.

I realize that by its very nature game design is a very subjective subject, but I feel that there's still got to be some sort of "rules of thumb" available. I have a very technical mind, so I struggle with these topics and would really like a baseline for basic exercises that a beginner should start with.

Thanks in advance!

There is no One True Source of Truth on game design.

I've worked with designers who start with a math heavy analytical approach, and compute heavy statistics on their white-box levels until they're satisfied it meets their criteria. I've worked with level designers who sit down with an editor and make many viewpoints beautiful first, then fill in more details to fit. Both work.

I've worked with game designers who started with a story and built rules around whatever fit their story. I've also worked with game designers who were handed a set of mechanics and they created amazing gameplay stories and themes from them. Still other designers start each level with a story; one of my co-workers on Fortnite started telling mini-stories with Gnomes years ago and the community has been raving about them ever since even though they have nothing to do with the main game.

There is no useless knowledge, anything you can bring to the game design is useful.  Number theory and game theory are great if you're looking for puzzles. Art theory, color theory, cultural uses of color, those are amazing for bringing emotional elements. Bringing in knowledge of world religions can help build deep cultural elements into game designs. Even random trivia and simple spelling can be brought into games and can stand alone, look at game shows like Jeopardy that is gambling over trivia questions and Wheel of Fortune that's based on creating words, or the plethora of word games where you're given six or seven letters and make every word from them.

There are thousands of books on the topic, with people describing how they approach the creative process. Use whatever works for you, for the games you're trying to create.