Technical blog post: https://sean-reid.github.io/blog/gravity.html
The idea: you're fighting near black holes, and Schwarzschild time dilation is the core mechanic. Get close to a well and the universe outside speeds up relative to you. Enemies move faster, projectiles zip past, weapons cycle quicker. Pull back out and everything normalizes. Single and binary black hole configurations make things pretty chaotic. Weapons and AI scale with local dilation, and there's procedural audio that shifts based on how deep you are in a gravity well. It's free, runs on Windows/macOS/Linux/web.
Built the whole thing solo: physics, AI, procedural audio, rendering, deployment. Happy to talk about any of the technical choices.