Question: Who was a creator of a science-fiction role-playing game along with Phil McGregor and an American game designer, notable for his work on "Space Marines" ?
Sentence (from "Space Opera (role-playing game)"): Space Opera is a science-fiction role-playing game created by Edward E. Simbalist, A. Mark Ratner, and Phil McGregor in 1980 for Fantasy Games Unlimited.
Relevant evidence: Yes