In 1984, Sierra published King's Quest to show off the advanced technology of the IBM PC. The success of that game set forth one of the most popular series Sierra has ever created, and spurred them into creating numerous adventure series based on the Quest theme. In the years to come Sierra would remain on the forefront of groundbreaking computer game design, sometimes creating large blockbusters and other times, failed experiments.
In 1991 Sierra started an online serviced called The Sierra Network. Pre-Internet, it was comparable to services like CompuServe or Prodigy except that its interface was completely graphical. Thematically it was a "kingdom" in which you visited different "lands" to post on message boardss, exchange emails and play games. It was renamed The ImagiNation Network and sold to AT&T in 1994 who sold it to AOL in 1996.
In 1996, the company was sold to CUC and Ken Williams left one year later. CUC later merged with HFS Corporation to form Cendant Software. After the discovery of an accounting scandal, Sierra was sold again to French publisher Havas who in turn were acquired by French giant Vivendi. Today, Sierra is part of the Vivendi Universal games group.
The company was renamed Sierra Entertainment in 2002.