I personally see Korean MMOs sterotyped as this:
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*They are almost always point and click minus a few exceptions.
*While all MMORPGS and RPGs in general have a level grind, Korean MMORPGs level grind is often unreasonably realistic. Taking hours to earn a few percent of a level.
*NPC/Mobs are re-colored and reused perhaps even more so than American MMORPGs/RPGs. This first started with Final Fantasy 1 in Japan if you want to take it back that far in RPG history.
*Most Korean MMORPGs are point and click with few relying on the keyboard for movement. This often makes combat or getting around in general fairly annoying due to the limited way of movement, it's like trying to control a RC car with one hand.
*Almost all Korean MMORPGs artstyle is almost always focused around anime. Making the games seem more generic than they should be. However, they spend a lot of time in this area making great looking art and graphics even if it's a similar style to other MMORPGs from Korea.