Generic Universal Roleplaying System
Steve Jackson created a system that would allow a game of anything the players imagination could build to be run.
There are a huge number of supliments for this game system. They are incredibly varied, ranging from swords and magic to B Movie Sci Fi thrillers.
Now this is a good idea but I have a number of reservations about this game system. It uses five attributes to describe a character, but almost all skills use only two of them. This leads to a strange setup for almost all of the characters.
So I do like the idea this system represents but find it a bit flawed when you actually come to play it.