Move fast and break things. What could possibly go wrong?
They use Bevy for ECS and custom rendering with Vulkan. It’s right there in the article:
Anastasia started with Bevy because it was the easiest thing to jump into, and we’re still using a modified version of Bevy to this day
Also mentioned in other places like this presentation: https://www.youtube.com/watch?v=jusWW2pPnA0
Protip: just do a nazi salute and Teslas will avoid hitting you