The Legend of Mir 2
This is another MMORPG that may be discounted by or unknown to western observers, especially those whose involvement with the genre doesn't go back at least a decade. Developed by a studio you may not have heard of, WeMade Entertainment, it launched domestically in the second half of 2001. It never managed to gain much visibility or to attract a sizable following in either Europe or here in North America, although it did fare well enough to operate for several years in both regions, until 2009 and 2012 respectively.
It Asia, Mir 2 followed a very different path. This is particularly true in China, where its success was unprecedented. It would be a gross over-simplification to credit any single MMOG with opening up what is now the world's largest and most lucrative national market. So, in terms of why I've included it in this list, think of it as representing a group. In any case, the game was pretty clearly the leader for a couple of years that saw very rapid growth, 2002-03. During this time, it reportedly topped out at more than 250,000 concurrent users.
Another notable reason is that to the best of my knowledge, Mir 2 appears to have been the first game that Chinese gamers could download at no charge and then pay for playing time. As such, it made the initial step toward the free to play business model that is now dominant there. Interestingly, it wasn't as PvP-centric as many of its contemporaries. The theme involved players working together to survive attacks by marauding monsters in order to rebuild human civilization.
MapleStory
If there's definitive evidence showing which Koren-made MMOG was the first to use an F2P revenue model, I'm not aware of it. That said, MapleStory is the one I remember as leading the way in terms of capturing my attention with this approach. Developed by another studio many westerners couldn't name, Wizet, it debuted domestically in the spring of 2003 under the aegis of Nexon, which subsequently licensed it out on a regional basis.
For me, this game is also significant because it aimed beyond the hardcore MMOG audience comprised of those who were playing Lineage, Mir 2, et al. While not completely casual, it was a 2D side-scrolling platformer in an industry environment where that was seen as an anomaly. The gameplay was and still is comparatively straightforward. Basically, you move about the world killing monsters and completing relatively uncomplicated quests to acquire experience, gear and currency. There's more to it than just this, but few if any of this site's readers would deem it more that moderately deep, if that.
This turned out not to be a problem because MapleStory tapped into a huge psycho-demographic market segment, one that doesn't include you or me except on an occasional basis when we happen to be in the mood for something less serious than usual. It demonstrated that there's enormous potential in aiming for those people who prefer easy accessibility and a gentle learning curve over greater complexity and challenge. Here again, while the full credit should be shared with other releases, Wizet's and Nexon's offering is, for me, the best single representative of this group.
Sudden Attack
Developed by GameHi, which subsequently became part of Nexon, Sudden Attack seems likely to be the most questioned entry on this list. The most obvious concern is that it's not a “traditional” MMOG. Depending on your personal definition of this term, it may not be one at all, but rather an online first-person shooter with persistent elements. For the purpose of this article, I'm not taking either side. I've included it because within the industry, more than enough people whose opinions I respect have chosen to call it an MMOFPS.
Released domestically in the spring of 2005, Sudden Attack changed the face of the Korean market. It quickly became the most-played online game there, surpassing all the MMORPGs and holding the top rank for some two years. To put this into its full perspective, you way want to note that it entered live service about three months after the regional debut of World of Warcraft. The former's arrival led the way in opening up a segment that has yet to approach a similar stature in this hemisphere despite attaining enormous popularity across most of Asia.
Like a couple of other titles on this list, Sudden Attack is no longer available in this region where it closed last year. It's still operating in much of Asia, but has been surpassed by various other games. For me, the most notable example is CrossFire, which peaked at more than two million concurrent users in China alone. It was developed in Korea too, but Sudden Attack is my pick for inclusion because it was the earlier of the two by a couple of years and thus the forerunner.