Looming Darkness
The World: Is a place where thousands upon thousands of planets and races converge. No discrimination, no differences, its a place for anyone and everyone. Well not for long, since that planet -which has 100x more mass than the Earth, collapsed. Well not literally, but the races inhabiting said planet had a fallout. All because of a single person, who brought destruction throughout the World then vanished without a trace. The only survivors are the common folk, whose limited knowledge had them hanging on the brink of destruction if they hadn't adapted to it.
The only place in the universe with the ultimate advancements in everything, became the most primitive planet with nothing but scattered knowledge for the remaining survivors in the universe. In human terms it could be seen as the modern people were thrown back to the Prehistoric period with danger at every corner due to lack of knowledge and dinosaurs.