DECO Online is a Free to Play/Free to Download MMORPG developed by Rocksoft and published in English by JOYMAX Interactive, and in Indonesian by PlayOn Interactive. DECO has no monthly subscription fees and instead the game features a Cash Item Shop. Cash Items aren`t required to play DECO Online, however they do offer an improved gaming experience. DECO Online has two nations, Millena and Rain. The Millena utilise weapons, however the Rain prefer using magic. Deco Online does contain a certain combo system, utilising the c, x, and z buttons (Similar to Seal Online)in order to perhaps alleviate the boredom associated with the usual point and click style of many other MMORPGs

DECO online consists of two nations, Millena and Rain, Millena is a nation that uses weapons such as swords and bows while Rain players use magic. The Millena race reside in Millena Town and its surrounding areas, unlike Rain that consists of mountainous regions Millena is surrounded by vast jungles such as Twinible Forest, Forest of Destiny and the Plains of Memory.

Millena players have the choice of becoming a Knight, Mercenary, Slayer or Sniper at level 30. Knights and Mercenaries both use Long Swords, while Slayers use Big Swords. Knights, Mercenaries and Slayers all use the combo system (C, Z, X) throughout the entire game, while Snipers do not. Snipers are the only job class in Millena that doesn`t require the use of the combo system.

Rain`s players reside in the mountainous regions of Unicle, the world that DECO Online is based in. Rain is comprised of magic users who do not make as much use of the combo system as Millena players do. Most of Rain`s job classes require partying with another player, such as Priests, Prominas and Psyches. The reasoning for this is because Priests have low attack, however they have the ability to heal other players and revive them without the use of potions and cash items, while Psyches have excellent defense and are great tankers however they have low attack.

At level 30 Rain Players have the choice of becoming a Holy Avenger, Priest, Prominas or Psyche. Holy Avengers and Priests use Staffs, while Prominas use books. Psyches are different and use Crystal Balls, however they attack with their fists and feet. They use the combo system like most Millena classes.