Knight Online is an MMORPG developed by MGame Corporation.
The original game is hosted by MGame in Korea, and requires players to enter their Korean resident registration numbers to register. There are three other official versions: Knight Online Xross (usually called "JPKO") is hosted in Japan, while Knight Online World (usually called "USKO") is hosted in the United States, and Knight Online Europe (usually called "EUKO") . All of these versions accept registration from any location.