Ars Magica is a role-playing game set in 'Mythic Europe' – a historically grounded version of Europe and the Levant around AD 1200, with the added conceit that conceptions of the world prevalent in folklore and institutions of the High Middle Ages are factual reality (a situation known informally as the "medieval paradigm"). The players' involvement revolves around an organization of magi and their allies and foes both mundane and supernatural. The game was originally developed by Jonathan Tweet and Mark Rein-Hagen, with its first edition published in 1987.
The current edition (the game's fifth) was written by David Chart, and published in 2004 by Atlas Games, who continue to develop new material for it.
Ars Magica was one of the first examples of a troupe system. Early editions recommended that the players collaborate to create the campaign world and story with: Each player having an opportunity to be Story Guide. (e.g. alternating by play session, 'chapter' of a story, or at the whim of the troupe) This scheme has been de-emphasised in recent editions; in Fifth Edition it is relegated to an optional play style described at the back of the book. Alternatively a troupe may select one player as the primary story guide responsible for the overall plot, and one or more secondary story guides who run peripheral sessions and/or stories. Each player having more than one character; when the primary character lacks opportunity or reason to participate in a session (typically due to laboratory or library activity), a secondary character is played.
To enhance the 'authenticity' of the historical setting, the game uses medieval Latin for a number of key terms, particularly in the game's most prominent feature, a system of Hermetic Magic.
History
The first two editions were published by Lion Rampant Games, with several modules published by Atlas Games. In 1991, Lion Rampant merged with White Wolf Magazine to form White Wolf Game Studio. White Wolf published several adventure modules for the game before adding its Third Edition rulebook, co-authored by Rein•Hagen with Ken Cliffe. This revision greatly expanded the settings and peripheral rules while leaving the core system intact. White Wolf then released at least a dozen supplements for Third Edition, including the addition of Divine and Infernal mechanics, rules for shamanic magic, beginning the Tribunal series and completing the 'Four Seasons' tetralogy of stories begun by Lion Rampant.
In 1994, publishing rights for the game were sold to Wizards of the Coast, who brought in Jonathan Tweet and started development on a fourth edition. The company published one supplement for the upcoming edition while republishing two supplements for the older edition. Development fell behind schedule, and on December 5, 1995, Wizards of the Coast announced they would leave the tabletop role-playing business altogether, although this turned out to be a temporary departure.
The next year the rights were sold to Atlas Games, who published the 4th edition developed by Tweet and Jeff Tidball. The core book was nominated for the Origins Award in 1996 for Best Roleplaying Game. Continuing to develop the line, Tidwell added several new stories, continued to expand peripheral material and released an extensive line of Tribunal books.
Atlas then assigned David Chart as line developer and released a 5th edition in 2004. This release made extensive changes to the system, especially the mechanics for combat, experience, and character creation. Many players felt that the alterations to the combat system were long overdue, especially the rules for armour, which in previous editions made wearers much more likely to die in combat. This edition won the Origins Award for Best Role Playing Game of 2004.
Since 2014, the 4th Edition has been distributed for free at Warehouse 23 fronted by Steve Jackson Games.
Many characteristics of the Storyteller system developed by White Wolf can be traced to Ars Magica and the fact that the Storyteller system was developed by one of Ars Magica's co-authors; White Wolf's Mage: The Ascension was envisioned as "Ars Magica in the Modern World", and many of the changes in the 3rd edition of ArM were to make the game-worlds more compatible.