Regnum Online is a fantasy massively multiplayer online role-playing game (MMORPG) developed by NGD Studios, a game development studio located in Argentina. In addition to usual character development present in other games of the genre, the game focuses on the conflict of 3 realms in which players take part, fighting against characters of opposing factions and capturing fortresses and castles aside from the usual player vs monster combats. The name Regnum means realm in Latin, and is also a tribute to one of the first games ever published in Argentina by some of the team members (which was named Regnum). It is frequently abbreviated as RO or ROL (which in Spanish also means role, as in role-playing games). The game was officially released May 24, 2007.

The game has currently more than 400,000 subscriptions and has received reviews in local newspapers, TV programs and in game-related websites (see External Links), as well as international sites spread throughout the world. NGD studios made a contract with Gamigo, a German gaming company and opened a German Server. Soon after, NGD added another German server to meet the demand for the game.

Players create characters as their avatars in a fantasy medieval-themed persistent virtual world. The first choice a player must face is selecting one of the three realms or nations: Alsius, icy home of the empire of dwarves, Nordos and Utghars; Ignis the desert homeland of the necromancer dark elves, humans and moloks; or Syrtis, the forested peaceful lands where elves, half-elves and Alturians live. Once a nation is chosen, the player may create a character (up to 3 per account) and customize it by choosing its race, gender, hair style and color, stature, etc. After choosing a realm and race, players go on quests and gain levels in the first two areas. After they have gained sufficient levels, they go to the third area which is called the War Zone, though a specific level is not required. In the War Zone, players can work together in clans or parties to take over enemy forts and castles or to simply hunt down their enemies.

Since the game originated from Argentina, there are a lot of players who speak Spanish but the game is slowly gaining momentum in the international community and there are already several players from countries all over the world. Depending on the time-zone, players may find other players that speak Spanish, English, German, Swedish, French, Polish, and many other languages. One by-product of the game having a small development team, was that the developers were always in touch with the players, creating a symbiotic relationship that helped improve the game over time. NGD Studios officially stated that they are planning on hiring a community manager that in turn will help create a volunteer`s program, thus embracing the community and opening the opportunity for those who want to participate. Current officially reported top 10 countries (in order), are Argentina, the US, Spain, Germany, Brazil, the UK, Chile, Canada, Mexico, and Poland.

Regnum offers 3 playable classes in each realm, each with 2 subclasses, one offensive, one defensive, attainable on reaching a certain level in the base class and completed the required quests. However certain races cannot play a certain class. For example the humans race can play as a Mage, Archer, or Warrior, but the Dwarf class from Alsuis can only choose the Warrior or Archer class. Characters from different realms have virtually the same possibilities, although as each realm has different races available. Once a character chooses the selected subclass, they will not be allowed to choose the other one, making the choice permanent. There are 5 Attributes for the character, Attributes are the areas that define your character.