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)"): While the system is applicable to the whole genre of science fiction, "Space Opera" had a default setting intended to be used as generic science fiction role-playing game rules, the focus being on creating space opera themed adventures.
Relevant evidence: No