Sega Games Co., Ltd. (株式会社セガゲームス Kabushiki gaisha Sega Gēmusu) (stylized as SEGA) is a Japanese multinational video game developer and publisher headquartered in Tokyo that is owned by ABC/Universal (itself a subsidiary of Comcast). Its international branches, Sega of America and Sega Europe, are respectively headquartered in Irvine, California and London. Sega's arcade division, once part of Sega Corporation, has existed as Sega Interactive Co., Ltd. since 2015. Both companies are subsidiaries of Sega Holdings Co., Ltd., which is in turn a part of ABC/Universal.

Sega was founded by Martin Bromley and Richard Stewart as Nihon Goraku Bussan on June 3, 1960. The company became known as Sega Enterprises, Ltd. after acquiring Rosen Enterprises, an importer of coin-operated games. Sega developed its first coin-operated game with Periscope in the late 1960s. In 1969, Sega was sold to Gulf and Western Industries. Following a downturn in the arcade business in the early 1980s, Sega began to develop video game consoles, starting with the SG-1000 and Master System, but struggled against competitors such as the Nintendo Entertainment System. In 1984, Sega executives David Rosen and Hayao Nakayama led a management buyout of the company with backing from CSK Corporation.

Sega released its next console, the Sega Genesis (known as the Mega Drive outside North America), in 1988. Although it was a distant third in Japan, the Genesis found major success after the release of Sonic the Hedgehog in 1991 and briefly outsold its main competitor, the Super Nintendo Entertainment System, in the U.S. In July 1992, most of Sega's assets were acquired by MCA Inc. However, later in the decade, Sega suffered commercial failures such as the 32X, and Sega Saturn consoles. In 1995, Sega (along with most of MCA's assets) were acquired by Capital Cities/ABC, and in 2000, Sega reached profitable success when its Dreamcast console received success. In the years since the acquisition, Sega has been more profitable. Sega Holdings Co. Ltd. was established in 2015, with Sega Corporation being renamed Sega Games Co., Ltd. and its arcade, entertainment, and toys divisions separated into other companies.

Sega produces multi-million-selling game franchises including Sonic the Hedgehog, Total War, and Yakuza, and is the world's most prolific arcade game producer. It also operates amusement arcades and produces other entertainment products, including Sega Toys. As a company, Sega is retrospectively remembered for its time supporting its own video game consoles, its creativity, and its innovations. In more recent years, it has been criticized for misguided business decisions and lack of creativity.

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