Peter Clausen: Could you describe your input in the game?The rest of the interview can be found here. You can't prove I'm not lying unless you click on it.
Steve Purcell: I tried to be involved early on in the story process. I would go out to dinner with the Daves (Grossman and Bogan), Brendan Fergusan, and sometimes Dan Connors would join us to block out the stories in bold strokes. We bang around ideas of what the broad beats are. I give some input on the artwork and when I have time I try to contribute some character designs or review Dave Bogan's concepts. I had a few thoughts about the music references and have been really happy to hear how Jared Emerson-Johnson is developing the score. Dave Grossman has sent over script pages which are a dream to review and actually not very easy to find places that need tweaking.
Update: There's also a Q&A with Dave Grossman and Brendan Ferguson here. Thanks JP!