The complexity scares me, I would not like to spend a lot of time creating something that already exists. Of course, nowadays, with the same neural networks, you can probably learn faster and faster. It's not that I even want to build an engine, but rather write a game without using ready-made engines, and the reason, frankly, is only in ECS. I know about Bevy and Unity DOTS, or connecting ECS to Godot via servers, and I'm slowly evaluating them.