From Sega Retro
Joypolis (ジョイポリス) is the name of several indoor amusement parks operated by Sega.
A likely result of Sega's strong growth of the late 80s and early 90s (particularly in the arcade sector), Sega envisioned opening indoor theme parks to expand its business and become one of the major players in the entertainment industry (reportedly at one stage during the 90s they were attempting to be world leaders, eclipsed only by the likes of Disney). This side of the business began with a park in Yokohama, Japan, which debuted in summer 1994, although the most significant Joypolis was the branch opened in Tokyo in 1996.
Typically a Joypolis acts as a glorified video arcade, with shops and restaurants and the capacity for other entertainment events, however its main contribution is housing some of Sega's medium and large scale attractions the company began designing and building in the late 1980s, such as indoor roller coasters and virtual reality simulators. It was unfeasible for big, permanent installations to be featured in typical arcade settings, so Sega effectively built its own parks to house these concepts. For example, obtaining the all clear for an AS-1 can be a challenge under normal circumstances, but by creating a Joypolis attraction, Sega could have one based permanently in a location to generate revenue.
Sega has opened numerous indoor theme parks based on the Joypolis model, although financial restraints of the late 1990s meant that many have since closed, particularly in regions where the traditional video arcade was losing customers to ever more powerful home video game consoles and computers. In Japan and similar Asian countries, arcades often fare better, so more Joypolis attractions have survived than SegaWorld or GameWorks centres.
The 11,946 sq metre complex opened with over 8,250 sq/m of that dedicated to the theme park's 7 major attractions. These included a revamped Virtua Racing (renamed Virtua Formula) and 217 coin operated arcade machines. Many of the rides also appeared inside Sega World Sydney when the parks launched in Australia. 
As part of a restructuring by Sega, Joyopolis Yokohama was closed in 1998.