Former Larian Studios (Divinity: Original Sin) tools programmer Dmitry Stepanov certainly has a passion for games programming, and engines in particular. In the past, he has created an entire 3D game engine in C, aptly called Dmitry's Engine. Now however, he's moved onto the Rust programming language and has since created rg3d.
rg3d is an open source (MIT license) 3D game engine written entirely in the Rust programming language. Why Rust? I don't know the author's actual motivations, but Rust sells itself as language with emphasis on performance and correctness. And many people find it to be a breathe of fresh air coming from other languages like C/C++.
Compared to most single-person created engines, rg3d is surprising mature. In addition to the core engine itself, there's also: rg3d-ui, for creating user interface elements; rusty-editor, a separate program for creating game scenes; and rusty-shooter, a 3D FPS demo that uses the rg3d engine.
The FPS demo ran quite well and was a good bit of fun to play around with. Unfortunately, I did have some troubles running the scene editor on my Ubuntu 20.04 machine. It was very slow and unresponsive to the point of being unusable, but I'm not sure how much of the blame lies on me or the application.
For a mostly one-person project, rg3d seems to have a lot of work put into creating it and making it usable for others. I'm interested to see how things progress, and maybe we'll be seeing games being created and released in Rust one day.
For more, check out rg3d on GitHub.