Short answers, pulled from the story.
Star Wars: The Roleplaying Game is a tabletop role-playing game set in the Star Wars universe, written and published by West End Games between 1987 and 1999. It used the D6 System, originally developed for the Ghostbusters RPG, and across three editions produced around 140 sourcebooks and adventure supplements.
West End Games sourcebooks established much of the groundwork for the Star Wars expanded universe. Lucasfilm sent Timothy Zahn a box of WEG sourcebooks when he was hired to write the Thrawn trilogy, directing him to base his novels on that background material. Alien names like Twi'lek, Rodian, and Quarren first appeared in WEG books and remained in use even after Disney's 2014 reboot of Star Wars canon.
Star Wars: The Roleplaying Game won the Origins Award for Best Roleplaying Rules of 1987 at the 1988 Origins Awards ceremony. In a 1996 reader poll by the UK magazine Arcane to rank the fifty most popular roleplaying games of all time, the game placed 9th.
West End Games lost its license to produce Star Wars material after the company declared bankruptcy in 1998. Wizards of the Coast subsequently acquired the license and held it until 2010, followed by Fantasy Flight Games from 2012 to 2020.
The Star Wars Adventure Journal was a magazine series published in novel format, running around 280 pages per issue. Fifteen issues appeared between 1994 and 1998, containing game adventures, articles, and short fiction intended to inspire gamemasters and expand the Star Wars setting.
The D6 System is the game engine that powers Star Wars: The Roleplaying Game, originally developed by West End Games for the Ghostbusters roleplaying game. It is designed around fast resolution and building narrative momentum, and encourages gamemasters to set aside rules whenever they might interrupt the flow of the story.