I’ve shared this guide in a few places already, and it’s been an incredible resource for me in better understanding how you can really bring a level together and what elements in the levels composition matter.
I recommend using this guide as a reference to help you develop your game levels rather than as a step-by-step, though it does make for some interesting reading. I find myself keeping it open on a second monitor when playing games trying to compare real examples with the examples in the text and it’s worked wonders in helping me break apart some of the better made decisions compared to the worse ones.
The guide covers pretty much every aspect of a level I can think of, ranging from how the level is constructed, how to demonstrate flow to the player organically within it, right down to how how important measurements between your players movement, size and field of view are. It also covers a large range of disciplines including both multiplayer competitive level design as well as single player narrative level design.
I hope it helps you all to produce better levels in your games!