Sierra Entertainment

Sierra Entertainment, Inc. (formerly On-Line Systems and Sierra On-Line, Inc.) was an American video game developer and publisher founded in 1979 by Ken and Roberta Williams. The company is known for pioneering the graphic adventure game genre, including the first such game, Mystery House. It is known for its graphical adventure game series King's Quest, Space Quest, Police Quest, Gabriel Knight, Leisure Suit Larry, and Quest for Glory, and as the original publisher of Valve's Half-Life series.

After seventeen years as an independent company, Sierra was acquired by CUC International in February 1996 to become part of CUC Software. However, CUC International was caught in an accounting scandal in 1998, and many of the original founders of Sierra including the Williamses left the company. Sierra remained as part of CUC Software as it was sold and renamed several times over the next few years. Sierra was formally disestablished as a company and reformed as a division of this group in August 2004. The former CUC Software group was acquired by Vivendi and branded as Vivendi Games in 2006. The Sierra division continued to operate through Vivendi Games's merger with Activision to form Activision Blizzard on July 10, 2008, but was shut down later that year. The Sierra brand was revived by Activision in 2014 to re-release former Sierra games and some independently developed games.

Following the acquisition of Activision Blizzard by Microsoft, the Sierra brand is under Microsoft's ownership through its gaming division.

Sierra Entertainment was founded in 1979 as On-Line Systems in Simi Valley, California, by the husband-and-wife duo Ken and Roberta Williams. Ken, a programmer for IBM, had planned to use the company to create business software for the TRS-80 and Apple II. Ken had brought a teletype terminal home one day in 1979 and, while looking through the host system's software catalog, discovered the text adventure Colossal Cave Adventure. He encouraged Roberta to join him in playing it, and she was enthralled by the game. After Ken had brought an Apple II to their home, she played through other text adventures such as those by Scott Adams and Softape to study them. Dissatisfied with the text-only format, she realized that the graphics display capability of the Apple II could enhance the adventure gaming experience. With Ken's help in some of the programming, Roberta designed Mystery House, inspired by the novel And Then There Were None and the board game Clue, using text commands and printout combined with rudimentary graphics depicting the current setting.

Mystery House was released through mail-order in May 1980. It was an instant hit with about 15,000 copies sold, earning US$167,000 (equivalent to $653,000 in 2025). It is the first computer adventure game to have graphics, although made with crude, static, monochrome, line drawings. The two shifted the focus to developing more graphical adventure games. Mystery House became the first in the Hi-Res Adventure series. The Hi-Res Adventure series continued with Mission Asteroid, which was released as Hi-Res Adventure #0 though being the second release. The next release, Wizard and the Princess, also known as Adventure in Serenia, is considered a prelude to the later King's Quest series in both story and concept. Through 1981 and 1982, more games were released in the series including Cranston Manor, Ulysses and the Golden Fleece, Time Zone, and The Dark Crystal. A simplified version of The Dark Crystal, intended for a younger audience, was written by Al Lowe and released as Gelfling Adventure.^{[citation needed]}

On-Line Systems was renamed Sierra On-Line in 1982, and moved to Oakhurst, California. The "Sierra" name was taken from the Sierra Nevada mountain range that Oakhurst was near, and its new logo incorporated the imagery of Half Dome mountain. By early 1984, InfoWorld estimated that Sierra was the world's 12th-largest microcomputer software company, with $12.5 million in 1983 sales. It produced some non-game software, such as an Applesoft BASIC compiler.

The company weathered the video game crash of 1983 with only a 20% increase in sales, after analysts in 1982 had predicted a doubling in 1983 of the entire software market. The company had spent much of 1983 developing for the VIC-20 and the TI-99/4A which were both obsolete by the end of the year. Ken Williams was reportedly described as "bewildered by the pace at which computers come into and fall out of favor", and Williams said, "I've learned my lesson. I'm not moving until I understand the market better."

Many of Sierra's best known series began in the 1980s. In 1983, Sierra On-Line was contacted by IBM to create a game for the new PCjr. IBM offered to fund the entire development and marketing of the game, paying royalties. Ken and Roberta Williams accepted and started on the project. Roberta Williams created a story featuring classic fairy-tale elements. Her game concept includes animated color graphics, a pseudo 3D-perspective where the main character is visible on the screen, a more competent text parser that understands advanced commands from the player, and music playing in the background through the PCjr sound hardware. For the game, a complete development system called Adventure Game Interpreter (AGI) was developed. In mid-1984, King's Quest: Quest for the Crown was released to much acclaim, beginning the King's Quest series.