I think I understand the concept of the Cortex system, adding the rolls for the skills together, and the Wikipedia page for the Cortex system says that I compare that roll to a difficulty number. In ...
From Serenity through Battlestar Galactica to the Stand-Alone Rules for Cortex, what has been changed?
I get the impression that the Cortex RPG system has evolved in several directions since the release of the Serenity RPG. Not including genre-specific changes like whatever rules for the supernatural ...