Mag Warriors is an MMORPG developed by MGame Corporation. With over 4.25 million subscribers and 8.91 percent of the current MMORPG market share, Knight Online is among the most popular games in the genre.[1] The original game is hosted by MGame in Korea, and requires players to enter their social security numbers to register. There are two other official versions: Knight Online Xross (usually called "JPKO") is hosted in Japan, while Knight Online World is hosted in the United States. Some people refer to Knight Online World as USKO. Both of these versions accept registration from any location. The Knight Online World version is popular in Turkey, and players from this country are an overwhelming majority in the game in many of the servers. Knight Online is free-to-play, but there are some features that must be paid for. In addition, there is an in-game Powerup Shop or Store which contains various items that one can purchase such as premium packages. Paid services include exclusive items and Premiums which are a limited-time subscription providing many benefits.

As in most MMORPGs, the player controls a virtual character and must collect experience points to gain levels and items that boost the stats of the character. The monsters that inhabit the game world can be attacked using melee attacks or skills. Once a monster is killed, the killing player gains experience points and the monster leaves behind a loot box which may contain Noahs (in-game currency) and other items. The drop box is only accessible to the player or party that did the most damage to the monster. However, in case of kill stealing, the experience is divided according to the amount of damage done. There are many quests in the game. These may require the player to kill a certain amount of a monster or to collect certain items (quest items). Other quests involve transportation of items from one character to another. The reward for the quests may include experience, Noahs, weapons and armor, or even the ability to use certain skills. Players are encouraged to be patient with collection of the reward because as they level up it becomes more difficult to accumulate experience. Players lose experience if they die from a monster. The amount lost depends on the character`s level and it`s also possible to lose a level upon losing experience. However, a death that results in a loss of a level will not allow the player to complete quests of the lower level.

As in most MMORPGs, Knight Online enables players to group together and complete objectives. Parties in Knight Online range between having two to eight players. The characters must be in a certain level range of the party leader in order to be in the same party. (However, a clan member may invite any other clan member regardless of level difference.) Party-members gain experience in accordance to their level. Knight Online encourages parties, since parties can collectively complete monster-killing quests. In general, players receive experience from monsters in accordance to their contribution of level within a party eg. in a party of a level 35 character and a level 45 character, the level 45 character will receive significantly more experience than the level 35 character per kill of a monster. The level 35 character will receive less experience than they might by killing the monster by themselves, and the level 45 character will get more experience than if he killed the monster by himself (nevertheless, the level 35 character will most likely receive more experience in general because the level 45 character will likely kill monsters much faster than the level 35 character could by themselves).

Noahs are split fairly evenly among players, and the total number of noahs a monster drops, is to some extent determined by the number of party members killing the monster. If the player doing the most damage to the monster is no longer eligible to receive noahs from a monster (because their level is higher than a certain threshold) then no noahs are dropped by the monster. For instance, a level 55 character will no longer receive Noah drops by killing "Lycans" so if that character does the majority of damage to the Lycan in a party, the party members will not receive any coin drop (but if their clan member, a level 20 character, does most of the damage then noahs will be distributed once clicked on).

Items are distributed in rotation among players, eg. if a "crystal" is picked up by any member of the party then whose ever turn it is to receive the item will get it. This results in party members deliberately picking up unnecessary or cheap items during other party member`s turns to pick up, or in some cases, players leaving the party while the treasure chest is open, and taking the item while not in the party if it is particularly valuable.