Question: Who is the owner of a small publishing firm focused on a series of related science fiction role-playing games, the first published in 1977 by Game Designers' Workshop?

full_context: Document 1: Roger Sanger: Roger Sanger is an American game designer and the owner of Digest Group Publications, a small publishing firm focused on the role-playing game market and specifically on the game "Traveller".
Document 2: 2300 AD: 2300 AD is a hard science fiction tabletop role-playing game created by Game Designers Workshop, originally offered as an alternative to the space opera portrayed by the company's leading science fiction role-playing game, "Traveller". In fact it was originally titled "Traveller: 2300", but this caused confusion as the game used neither the rules system nor the setting of the original "Traveller". The game was therefore renamed in its 2nd edition.
Document 3: Striker (miniatures game): The miniatures game Striker was a science fiction tactical wargame that was published by Game Designers' Workshop in 1981 as a boxed expansion to the "Traveller" role-playing game. It was notable for attempting to cover a broad range of technological levels and having an intricate "engineering" style of vehicle design by the player using formulas and tables. The combat rules were an elaboration on the rules introduced in the Azhanti High Lightning game, using a 2D6 mechanic very different from the original "Traveller" rules. A later game, "Striker II", was based on the systems in GDW's Command Decision World War II rules and tied to the role-playing game "".
Document 4: Sam Lewis (game designer): Sam Lewis is an American designer of board games and former line developer of the "Renegade Legion" line in FASA Corporation. He was also president of FASA for a time.
Document 5: Don Greenwood (game designer): Don Greenwood is a board game designer and was a pioneer editor among commercial board-wargaming magazines. He began his own fanzine, "Panzerfaust Magazine", which he oversaw from 1967 until 1972. He then joined The Avalon Hill Game Company in 1972, and took over editorship of that company's "house organ", "The General Magazine", which office he held until 1982. He left Avalon Hill and continued to work in the wargame industry, notably for GMT Games. He is the founder of the Origins, Avaloncon, and WBC gaming conventions and remains the WBC convention manager. Greenwood is also president of the Boardgame Players Association. He was inducted into the Origins Award hall of fame in 1991 and the Charles Roberts Awards Hall of Fame in 1994. He was honored as a "famous game designer" by being featured as the king of spades in Flying Buffalo's 2011 Famous Game Designers Playing Card Deck.
Document 6: Palladium Books: Palladium Books is a publisher of role-playing games (RPGs) perhaps best known for its popular, expansive "Rifts" series (1990–present). Palladium was founded April 1981 in Detroit, Michigan by current president and lead game designer Kevin Siembieda, and is now based in Westland, Michigan. The company enjoys the support of a small but dedicated fanbase who praise its various game series for their innovative settings and ease of adaptability to various personal preferences, play styles, and power levels.
Document 7: MegaTraveller 2: Quest for the Ancients: MegaTraveller 2: Quest for the Ancients is a 1991 space science fiction role-playing video game produced by Game Designers Workshop licensee Paragon Software and distributed by MicroProse and Empire Software. It is the sequel to "". Designed by Marc Miller, an original creator of the "Traveller" series, the game is set within the "Official Traveller Universe" and features a character creation system and other elements of game mechanics compatible with previous "Traveller" products. The game's plot centers on finding a way to stop the flow of slime issuing from an ancient ruin on the planet Rhylanor before it inundates the entire world. Gameplay involves controlling a party of up to five adventurers who engage in real-time exploration, trading, interaction with non-player characters, combat and problem solving on the surface of over a hundred planets and in spaceships journeying between these worlds.
Document 8: MegaTraveller 1: The Zhodani Conspiracy: MegaTraveller 1: The Zhodani Conspiracy is a 1990 space science fiction role-playing video game based on the "Traveller" series and was produced by Game Designers' Workshop licensee Paragon Software for Amiga, Atari ST and MS-DOS operating environments. The game is set within the "Official Traveller Universe" and features character creation and other aspects of game mechanics compatible with prior "Traveller" products. The player controls up to five ex-military adventurers whose objective is to save their civilization, the Imperium, from a conspiracy instigated by the Zhodani, a rival spacefaring race, and aided by the actions of a traitor named Konrad Kiefer. Gameplay features real-time planetary and space exploration, combat, trading, and interaction with various non-player characters in eight solar systems containing twenty-eight visitable planets.
Document 9: Tri Tac Games: Tri Tac Games is a publisher of role-playing games based in Pontiac, Michigan. The company is built primarily on the work of Richard Tucholka, its founder and president.
Document 10: List of Traveller Books: "Traveller" is an Origins Award winning science fiction role-playing game published by Game Designers' Workshop in 1977. In the Third Age of the Imperium interstellar travel has become possible and Humaniti has met other starfaring races. 2300 AD portrayed humans as technologically advanced, but having a level of civilization not very far above the present day. Later publishers introduced additional material along the Official Traveller Universe (OTU) timeline. In 2008, Mongoose Publishing reintroduced GDW's popular look and indexing feature separating publications into familiar Books, Supplements, and Adventures.
Document 11: Traveller (Slough Feg album): Traveller is a concept album by the American folk/power metal band The Lord Weird Slough Feg. The album is based on Game Designers' Workshop's 1977 science fiction role-playing game, "Traveller".
Document 12: Steve Peterson (game designer): Steve Peterson is a game designer who has worked primarily on role-playing games.
Document 13: Starship Traveller: Starship Traveller is a single-player adventure gamebook written by Steve Jackson and illustrated by Peter Andrew Jones. Originally published by Puffin Books in 1983, the title is the fourth gamebook in the Fighting Fantasy series. It was later republished by Wizard Books in 2002. A digital version developed by "Tin Man Games" is available for Android and iOS.
Document 14: Traveller (role-playing game): Traveller is a series of related science fiction role-playing games, the first published in 1977 by Game Designers' Workshop. Marc W. Miller designed "Traveller" with help from Frank Chadwick, John Harshman, and Loren K. Wiseman.
Document 15: Frank Mentzer: Jacob Franklin "Frank" Mentzer III (born in 1950), is an American fantasy author and game designer best known for his work on early materials for the "Dungeons & Dragons" (D&D) fantasy role-playing game. He was a performing folk musician from 1968 to 1975, and played one concert at the White House during the administration of Richard Nixon. He was an employee of TSR, Inc. from 1980–1986, spending part of that time as Creative Advisor to the Chairman of the Board, Gary Gygax. He also founded the Role-Playing Games Association (RPGA) during his time with TSR. He has been closely involved with the world's largest game auction at the Gen Con game convention since 1983, and is an expert on, and a major collector of, family boardgames and role-playing games. After Gygax was ousted from TSR at the end of 1985, Mentzer left TSR as well and helped him to start New Infinities Productions Inc. (NIPI). When this venture failed, Mentzer left the gaming industry, eventually becoming the manager of a bakery. In 2008, he closed down this business and, two years later, announced he was returning to the gaming industry as a founding partner of a new publishing company, Eldritch Enterprises.
ground_truth: Roger Sanger