An arcade game or coin-op game is a coin-operated entertainment machine typically installed in public businesses such as restaurants, bars and amusement arcades. Most arcade games are presented as primarily games of skill and include arcade video games, pinball machines, electro-mechanical games, redemption games or merchandisers. Broadly, arcade games are nearly always considered games of skill, with only some elements of games of chance. Games that are solely games of chance, like slot machines and pachinko, often are categorized legally as gambling devices and, due to restrictions, may not be made available to minors or without appropriate oversight in many jurisdictions. An arcade video game takes player input from its controls, processes it through electrical or computerized components, and displays output to an electronic monitor or similar display. All arcade video games are coin-operated or accept other means of payment, housed in an arcade cabinet, and located in amusement arcades alongside other kinds of arcade games. Until the early 2000s, arcade video games were the largest and most technologically advanced segment of the video game industry. Early prototypical entries Galaxy Game and Computer Space in 1971 established the principle operations for arcade games, and Atari's Pong in 1972 is recognized as the first successful commercial arcade video game. Improvements in computer technology and gameplay design led to a golden age of arcade video games, the exact dates of which are debated but range from the late 1970s to mid-1980s. This golden age includes Space Invaders, Pac-Man, and Donkey Kong. The arcade industry had a resurgence from the early 1990s to mid-2000s, including Street Fighter II, Mortal Kombat, and Dance Dance Revolution, but ultimately declined in the Western world as competing home video game consoles such as the Sony PlayStation and Microsoft Xbox increased in their graphics and gameplay capability and decreased in cost. Nevertheless, Japan, China, and South Korea retain a strong arcade industry in the present day.
Near the end of the second tournament, Kei Ikushima, after defeating Regulus in the finals, discovers that the underground laboratory's self-destruct mechanism has been activated. As she was about to make her escape, she would end up crossing paths with Eileen A. once again. Kei tried to escape the lab with Eileen, but she hesitated, instead telling Kei the answer she was looking: Kei was actually the daughter of none other than the CEO of Orion Corporation, Ranzou Kihara. She then gives Kei a letter before telling her to go on and leave the building without her. Kei hesitates at first but soon obliges as the lab eventually explodes, leaving Eileen behind, her fate unknown. Three years after the explosion at the Orion labs, Kei finds out more about her past from the letter Eileen gave her before the incident. She also found out that her DNA was taken for usage in Orion's Perfect Fighter Project, the very same set of experiments that orphaned her adoptive father Shin and ruined the lives of many others. Fast forward to several weeks before Kei’s 20th birthday, several attacks on various martial artists have been reported. All of them perpetrated by people who bore a striking semblance to Kei. As a result, Kei has been blamed for all the attacks, despite having no hand on them. Kei then began to suspect that it had something to do with the Perfect Fighter Project that Eileen had mentioned. Then, on the day of Kei’s 20th birthday, Orion announces the third Sentoki: Global Martial Arts tournament. Kei joins the tournament in order to cleanse her name and find out the truth of it all.
