Obsidian also included other factions from previous "Fallout" games and avoided writing any faction as entirely good or evil, but instead as potential rivals depending on what path the player decided to pursue. The game had a somewhat short development cycle of 18 months. "New Vegas" is similar to "Fallout 3", in that both games use the Gamebryo engine, yet it improved on the previous installment's source code, with some graphics rendering improvements and new art assets, while also reworking the engine to accommodate the extra lights and effects of the Las Vegas Strip. Obsidian were unfamiliar with the Gamebryo engine and had to request the help of an Oblivion modder named Jorge Salgado. Obsidian also refined the real-time shooting mechanics and added iron-sights aiming to make playing without V.A.T.S. a more viable option than it was in "Fallout 3". One PC version of the game relies on Steamworks for online functions, such as achievements and cloud save storage, as well as DRM. A version without DRM was made available by GoG.com on June 1, 2017. Producer Jason Bergman announced the involvement of several celebrities, including Ron Perlman as the game's narrator and Wayne Newton as radio DJ "Mr. New Vegas". He also confirmed that the game would include voice acting from Matthew Perry, Zachary Levi, Kris Kristofferson, Danny Trejo, Michael Dorn and Felicia Day. The team brought on casting director and voice producer Timothy Cubbison to oversee the actor selection and voice production. The game established the new record for the most lines of dialogue in a single-player action role-playing game. The game contains around 65,000 lines of dialogue, beating its predecessor and previous record holder "Fallout 3" which contained 40,000 lines of dialogue. "Fallout 3" composer Inon Zur composed the score for the game. The game features three major in-game radio stations, spanning several genres of music in the radio waves: country, bluegrass, popular music from the 1940s and 1950s, jazz and classical. Each station has a set track list which repeats randomly. Music from the first two "Fallout" games, composed by Mark Morgan, is used in the game as well. On February 4, 2010, Obsidian Entertainment released the "Fallout: New Vegas" teaser trailer. A second trailer was first shown on GameTrailers from E3 on June 11, 2010. Bethesda announced four pre-order bonus packs giving specific in-game items, they include the "Classic", "Tribal", "Caravan" and "Mercenary" packs available when pre-ordering at specific outlets, all of the listed pre-order packs were later made available for purchase on September 27, 2011.