The universe can only do what's possible, so when we found out that there was no solution to the three body problem, it was only a matter of time before we proved that the universe wasn't using the simple abstracts we kept on simulating it with. Before long, we found out that there was a smallest time step, and soon after that we found out that time dilation was purely down to load balancing. We found a back door into the balancing act and soon enough we had faster than light travel as we sucked cycles from the universe. Travel around the universe was quick and cheap. After decades of research, and some observations of our own planet (by taking videos of our planet from millions of light years away) we found that humans were in fact visited by aliens a long time ago, but research into where these aliens came from lead to a point in space on the far side of Pluto. The aliens hadn't come from there, they had just materialised.
Pluto wasn't a planet, not even a planetoid. It was a spawn point.
Then, the hunt was on to figure out which ones of us were the NPCs, and which where the Players.