of With Teeth. Many critics also commented on the album's overall tone, including descriptions such as "lots of silver and grey ambience" and reference to the album's "oblique tone". The New York Times review described the album's sound by saying "Hard beats are softened with distortion, static cushions the tantrums, sneaky bass lines float beneath the surface." The article went on to describe individual tracks: "And as usual the music is packed with details: "Meet Your Master" goes through at least three cycles of decay and rebirth; part of the fun of "The Warning" is tracking the ever-mutating timbres." Many of the songs on the album feature an extended instrumental ending, which encompasses the entire second half of the three-minute long "The Great Destroyer". The album was co-produced by Reznor and Atticus Ross, mixed by long-time collaborator Alan Moulder, and mastered by Brian Gardner. The album features instrumental contributions by live band member Josh Freese and vocals by Saul Williams. Themes Nine Inch Nails' 2006 tour merchandise designs featured overt references to the United States military, which Reznor said "reflect[ed] future directions". Reznor later described Year Zero as "the soundtrack to a movie that doesn't exist". The album criticizes the American government's policies, and "could be about the end of the world". Reznor specifically cited what he labeled as the "erosion of freedoms" and "the way that we treat the rest of the world and our own citizens". Reznor had previously called the results of the 2004 US election "one step closer to the end of the world." Even though the fictional story begins in January 2007, the timeline of the album and alternate reality game mentions historical events, such as the September 11 attacks and the Iraq War. From there, fictional events lead to worldwide chaos, including bioterrorism attacks, the United States engaging in nuclear war with Iran, and the elimination of American civil liberties at the hands of the fictional government agency The Bureau of Morality. Regardless of being fictional, a columnist of the Hartford Courant commented, "What's scary is that this doesn't seem as far-fetched as it should, given recent revelations about the FBI's abuse of the Patriot Act and the dissent-equals-disloyalty double-speak coming out of Washington in recent years." Artwork All of the artwork for Year Zero was created by Rob Sheridan, art director for Nine Inch Nails, who is also credited for artwork on With