A Dream about Real Virtuality

This night I had an interesting dream. I visited a friend and he showed me a website with some kind of virtual world. Basically it was like a computer game where you could walk around in a 3D world.
It all started in a room where some people were walking around. I could move around with the mouse in my hand. I zoomed out and suddenly flew through the roof of the building. Then I saw something interesting: the building was a temple, but it was small, some kind of model. It was about 20cm in height in terms of "outer-world" measures. The outer world was a whole city. You could fly around in it, watching people, cars and of course buildings.
So I navigated a little through that world and zoomed into another house. There was a little girl looking at some kind of fish tank. On the water surface there was a little boat. I zoomed into that boat because I was curious how many details there were. And to my surprise, I could zoom into that boat and there were people in it. They were alive. I saw a mother with her little baby. I could click on them and they would talk. I left the boat and was out in the "big world" again. So I tried clicking on the little girl watching the boat and she talked, too.
I kept flying around in that world for hours (in dream time). The details were amazing. Thousands of buildings and even more people and cars. It was a mega city. I kept asking myself, since this was a computer program: who created all this. Maybe it was some kind of second life 10.0 . I never played that game in real life, yet that dream was so amazing that I would love to see such a game - or simulation in real life.
After waking up I imagined how it would be possible to create such a simulation in real life. It would be an amazing project, a whole civilization simulated on a computer. And most of all: I do not doubt that this will be reality one day.