The Korean gaming company Nexon is one of the most underrated Internet companies in the world. Nexon was, it is fair to say, the first company to experience massive success with a business model built on selling virtual items. Building from their wild success with the Mario Kart-like racing game, Kart Rider, Nexon created a gaming empire first in Korea and then around Asia. This empire was unprecedented and it opened up a whole new way of thinking about making money off of gaming.
Nexon brought all kinds of different game types to the Korean market, and soon thereafter, to China both through their own efforts and through copycats. At the time, the Asian markets were considered a sinkhole by Western publishers because the retail business they depended on in the west didn't work. Instead of going into stores and buying games, piracy ran rampant and western game makers couldn't figure out how to make money. Nexon cracked the code, creating monetizable games by completely chucking the retail model that had succeeded in the west.
It should also be noted that when Nexon was doing all this stuff in the early and mid-2000s, no one was paying for anything on the Internet. Many people weren't convinced that anyone would ever buy anything virtual on the Internet, let alone virtual items for a game*. So their success wasn't just significant for gaming but for all Internet companies. They proved that if you tuned your content right, people would pay for bits.