Interesting to hear your experience with Rust. I’ve also been working on a game project for a long time, but in Unity. It’s bothered me for a long time that I have to be so reliant on the editor when using Unity, because I feel like as a programmer, man I could just be so much more productive if I was _only_ coding all day long!
But over time I’ve realized that the Unity editor is actually a really important piece of the development tools for games. Games are an extremely visual medium. So it’s really important to have something that is at least mostly WYSIWYG.
Something I've played with off and on is using blender for all the key bits engine editors provide. You can encode metadata (components, pipeline steps) on 3d objects with the extra properties fields. Every GLTF importer I've tried will expose them to you. It's just json after all.
You can write a client in C# that renders the 3d bits in about 45 different ways. In the browser you could use Three.js. For some projects, I think an engine is optional.
But over time I’ve realized that the Unity editor is actually a really important piece of the development tools for games. Games are an extremely visual medium. So it’s really important to have something that is at least mostly WYSIWYG.
(My game project: https://pollywog.games/barnards-star.html )