Have done a simple Google search using key words "Korea gaming". I got 3,310,000 results.
I have also tried lexxe, the talked about new generation search engine powered by advanced natural language technology. The question I used was "top players in korea gaming industry". I got 5 results.
This article is about GSTAR, largest Korean game show. 2 other results from Lexxe are basically duplicated and the rests are useless.
I then used a new question as "list of companies in korea gaming industry" then I got 100 results. That's more like it. There is one useful there at news.com which says "NCSoft's medieval role-playing game "Lineage" is the most popular online game in the world, with more than 4 million subscribers, mostly in Korea". There is also useful link to List of Stocks for gaming industry. I found elsewhere that quite a few Korean companies have been listed in NASDAQ. The list there is quite long therefore I have to click links there one by one to see if they are Korean. One other article mildly related can be found at The Industry Standard is about fast growing online gaming industry in China. Last but not least is the famous report from Market Research.com which costs you US$475.
I'll go back to Google's search results from here.
This article in BBC News tells you how South Korea is one of the most "wired" societies in the World. There are more than 25,000 cyber cafes across the country. These are called "PC bangs" which operate 24 hours a day.
We are talking about gaming therefore can't ignore the official site World Cyber Games. There are a lot at this site if you have time to look inside.
After you read this post at gamestudy.org you'll be scared to know that the Virtual World is as dirty as the real one. From this article at MSNBC you'll know that selling virtual goods for real cash is not illegal in Korea. Also read from there that the largest online auction company in Korea is Itembay but too bad they only have a website in Korean. Also a gaming expert at Yonsei University in Seoul (named Asia's best universities 2000 by Asiaweek) is called Whang Sang-min.
From this archived article by Electronic Gaming Business it was said that Korea has the highest broadband Internet penetration in the World. You will also see that quite a few Korean firms have done fundraising in the US in 2003, they are Netamin and Unibox Korea.
This site by GameDailyBiz has a lot of information. The Korean Government has been helping the industry and they have KOCCA, short for Korea Culture & Centent Agency, to help. By the way KOCCA has branch office in Bejing, Japan, USA and Europe. It was said that the Korean online game market is the largest market in the Asia/Pacific region based on online game subscription revenues. According to IDC, by 2008 the subscription revenues in Korea are expected to grow to $586 million.
It's also found from this article that the other 2 key players in the business are Gravity Interactive and Webzen.
This article by news.com tells you more about key players Webzen and Gravity from Korea. Another article by BusinessWeek Online tells you how successful NCSoft is and these Korean firms are making big bugs and going for the global market of $18 billion industry which is still essentially dominated by US firms.