The universe is a boundless big thing, but to imitate it and create a small universe, all it takes is one planet. I usually use Blue Star data to set parameters so that intelligent life can emerge and survive, develop freely, and build their own civilization. Unfortunately, there are still bottlenecks in small universe technology. I don't know why, but every small universe will suddenly come to an end after a few billion years. I couldn't predict it and I couldn't stop it.
Purpose: Romance till death do us part