From the E3 Q&A transcript:
Crowd Member: Where, for the whole marathon series, and for that a while ago, what kind of gave you your idea for starting the whole series of games, the whole Marathon series?
Brian: And why the apostrophes?
Jason: That's an impossible question to ask, really, I think that Marathon was sort of the project of three or four college students for two or three years talking about all kinds of different sci-fi, working on as many new ideas as they could to try to do something cool, that's a dumb way to say it, but you don't know where those ideas come from when they finally jump in and become real. It's even more than two or three years probably... it's probably every book I've read since I could read. So I can't really answer it very well... sorry. Sorry about that. In that interview I did last year, I talked about some of the books that maybe influenced me most, like Starhammer. That's probably the best I can do. I'm always thinking about new ideas.
