The score that Trent Reznor and Atticus Ross composed for HBO’s limited series “Watchmen” could be boiled down to this: It was the most Nine Inch Nails of times, it was the least Nine Inch Nails of times. Which is to say, their work on the thoughtful science-fiction drama took them as close to their rock ‘n’ roll day job (or night job, depending how you look at it) as any film or TV scoring project ever has. And then, with a nod to the show’s premise, it took them into some alternate universes.

When they came to the producers with some initial ideas for music for the pilot, “the music that they were really digging wasn’t that far away from some stuff we would do in Nine Inch Nails,” Reznor says, talking about how well the driving electronic music they’ve done under that aegis fit in here. “And we’d never had an opportunity in a scoring situation to explore that as directly. So once we took the cue from them, we were off to the races.” Among the initial pieces that got used for that first episode were the John Carpenter-esque theme “How the West Was Really Won” and “Nun With a Motherf*&*ing Gun,” a bit of action-sequence soundtracking that set NIN fans’ hearts racing. “I think we started to think, ‘Oh, this is going to be easy, because this is kind of like what we do in Nine Inch Nails.’”

Although the duo would hardly ever want to be accused of coasting, there was a stylistic familiarity there they assumed they might be able to keep up through the remaining episodes… wrongly, as they describe it. Says Reznor, “As our camps became more familiar with each other and a true friendship emerged, it wasn’t one to rest on laurels. What was being asked began to exponentially increase.” Ross describes it this way: “The more kind of in-your-face stuff, there’s a lot of it in episode one. But then it became a very broad spread for the score in terms of the way it goes from a gospel choir to a 1940s period song.”

The faux period tune in question, “The Way It Used to Be,” with vocals by Laura Dickenson, became one of the most talked-about pieces of original music in the show… once fans realized it was original music and not a needle drop. “In episode six, when we’re in the 1940s, we could have dropped in an actual vocal piece from the 1940s to play over the lynching scene,” Reznor says. “But we’d get the phone call, with not quite enough time ahead of it, saying, ‘Do you think you could come up with something that does this?’” The resulting track was finished “in about a week — it was coming in hot… I think the truth of the matter was, they had had a Doris Day track in there that the publisher wouldn’t license. I think publishers learned their lesson about haunting music against horrifying images. I mean, after (Roy Orbison’s) ‘Candy Colored Clown’ became imprinted with ‘Blue Velvet,’ I’ll never hear that song and not think of Frank Booth puffing on nitrous.’

“Anyway, a lot of those things started to get asked,” Reznor continues, “because Damon (Lindelhof) thought it would be better if we did it rather than drop in something easy. There were moments of extreme panic: ‘How in the hell are we going to record a big band that sounds exactly like something from 1940 with a vocal that fits over this scene, and can we get that done in less than a week? Can we even write a song like that?’ But those sorts of things inside a very loving, trusting, respectful and exciting atmosphere made it end up being fun. We came out the other end with something that was in some ways not that far outside the wheelhouse of Nine Inch Nails, and in other ways, as far out as we’ve ever gone. Against the condensed timeline of doing television — it was like a nine-hour movie, in a third of the time we would do a regular film – we felt like we’d moved into something we’ve never done before and came out satisfyingly exhausted.”

Ross also points to the instrumental cover of David Bowie’s “Life on Mars” Lindelhof asked them to contribute as something that “I suppose ‘difficult’ or ‘scary’ could be applied to. I didn’t have a friendship with Bowie like Trent did, but that’s hallowed ground. One, it’s a pivotal moment in the story, and two, it’s one of the best songs ever written, and it’s not something you want to fuck up.” Reznor says, “We didn’t want to let Damon down and thought, ‘ If it sucks, we won’t let him hear it.’ But it led to something that ended up being, I think, quite beautiful and something we’re very proud of.”

The pride extends to the overall project and how it expanded a fantasy premise and dealt with race. “I was curious to see what Damon would do with a property that is fraught with danger of how you could ruin it,” says Reznor, “even before finding out that what he wanted to do with was incredibly daring, not only in terms of his respect for the canon, but a fearlessness in re-appropriating and re-juxtaposing things to take on a hot-button, culturally relevant social issue today.”