In the late 1980s, SNK developed an arcade system that could work with multiple games. They called it the Multiple Video System. It used cartridges, like a game console. A home version was the logical extension, and thus was born the Neo Geo Advanced Entertainment System. The MVS itself turned out to be the longest-lived arcade hardware of its kind, outlasting Nintendo's VS. hardware by several years.
However, arcade machines cost a lot more than home consoles, and SNK knew that. At first, it was a luxury item for rent in hotels. When guests started letting the company know they'd be willing to buy them, SNK decided to put it on sale. The Neo Geo was released to the general public in January 1990.
The cost was high, not just for the processing power, but for the joysticks and games. The games cost about $200, partly because their size was comparable to N64 carts and partly because of their architecture — the RAM chips needed to play the game were built into the cart rather than in the system. The system launched in the US, with two controllers and the game Magician Lord, at $650. Just a bit later, a bundle with no game and one controller sold for $400. In an attempt to cut the price, SNK released the Neo-Geo CD in 1994. It was $300, and games were $50, but with a 1x CD-ROM drive it fell victim to Loads and Loads of Loading.
The price of the system and games meant the mainstream was out of the question, so SNK went for Up Marketing to appeal to hardcore gamers, who actively embraced the system just as they would the Sega Dreamcast a few years later. This had some initial success, but unfortunately that cost didn't go to proper anti-piracy measures, and the system was rife with it. SNK blamed that as a major factor in their bankruptcy in 2000, though the Neo-Geo managed to not only survive their collapse but last long enough to see their reconstitution as SNK Playmore.
The final Neo-Geo game, Samurai Shodown 5 Special, was released in 2004. But the Neo-Geo lives on, with collectors and some people are making homebrew games for it years after the system was discontinued.
Not to be confused with the Geo sub-marque of Chevrolet that existed at about the same time as the Neo-Geo's heyday.