I made my game wothout an engine in Rust and wgpu (a wrapper around Vulkan and DX12) with a custom render pipeline, quite possibly creating the first non-RTX game to support physically-accurate refraction (which I’ve turned into a core mechanic).
https://george-steel.itch.io/bowfishing-blitz
Source is available at https://github.com/george-steel/bowfishing-blitz