Diane Haithman is contributing to Deadline’s TCA coverage.

Syfy’s Defiance — a drama series that will exist as both a TV series and a video game in collaboration with Trion Worlds — will have its series premiere April 15 at 9 PM with a two-hour episode launching a total of 12 episodes, the cable channel announced today at TCA. During today’s panel featuring the show’s cast, executive producer Kevin Murphy and Syfy president Mark Stern, Murphy said that although the producers of both the TV show and the game will collaborate on creating parallel realities, players of the game will have no influence over major plot points in either one.

It’s not an “audience vote” adventure, Murphy said. “The analogy I like to use is, I grew up as a gigantic comic book geek, and what I loved about comics is that you could love Batman and read Batman’s adventures, and if you happen to also like Superman, if you read both titles, sometimes there would be crossovers in the summer that lent an extra level of coolness to the whole thing.”

Added Murphy, “The game has its own narrative and story lines. They are shared universes with dual portals. If there is a catastrophic weather experience [in the TV show], the characters in the game [may] put that in motion.” He said the game will create an illusion of spontaneity, but “if you are supposed to get the gadget, you will get the gadget.”

Because the game and the TV drama contain overlapping stories and characters, Stern said, “there was definitely no aspect of this deal-making that was normal. Lawyers love that. Agents love that.”

The show, set on Earth, depicts a futuristic boomtown set on the ruins of St. Louis that is now home to seven alien species and Earthlings. It represents quite a contrast from Murphy’s short-lived cheerleader series Hellcats (he is better known for Desperate Housewives and Caprica). When asked whether he associates himself more with Defiance than Hellcats, Murphy quipped: “It [Hellcats] was not my idea, I was told I was one of the approved people” to run the show. “My agent said ‘Don’t be a snob, you haven’t sold anything in a year’ ”.

Eventually, however, he said that he came to appreciate the story of aspiring cheerleaders as comparable to those of struggling actors in Equity Waiver theater.

On the panel, Murphy said he retooled Defiance when he it took over as showrunner from Rockne O’Bannon, who remains an executive producer but left the show to run the CW series Cult. After the panel, Murphy said that he had been brought in as the “transition guy” to aid in developing O’Bannon’s original script and vision, but would not have taken over the show unless he was free to put his creative stamp on it. He added that Stern approved him making the show his own.

Murphy said he decided to make Defiance “much newer” in the sense of bringing in characters that were new to the town of Defiance in various ways, rather than having old-timers dominate the action. “I wanted to see people make mistakes,” he said.