@Mr Allen J That's awesome, and honestly one of the elements I rely heavily on in my roleplays. There is no possible way to document and define
every concept that is possible in a roleplay world, or even just in the area in which the roleplay is taking place. If it's space exploration, what about new technologies or new races? What about new planets? There is no way to even count the number of possible planets, because as far as we know, there is no end to space.
So, allowing players to introduce content is a powerful tool to expand your roleplay. It gives new plot, new opportunities for characters, new NPCs... I wonder why more GMs don't allow it.
Naturally, I would seek GM approval for anything drastic, but...awesome.
Side Note: I am not above editing posts, if I introduce content which is found to be utterly retarded.