The game system is rather innovative, with everything based on d10. The heart of the game (not surprisingly) is the magic system: There are 15 "Arts" divided into 5 "Techniques" & 10 "Forms". The Techniques are what one DOES (actions); the Forms are what one does it TO or WITH (objects); this is sometimes called a "Verb/Noun" magic-system. Spell-casting is the act of combining a Technique & a Form under the will of the wizard. The Arts are named in Latin; the Techniques are: Creo, Intellego, Muto, Perdo, & Rego (actions Create, Perceive, Change, Destroy, & Control); the Forms are: Animal, Auram, Aquam, Corpus, Herbam, Ignem, Imaginem, Mentem, Terram, & Vim (objects Animal, Air, Water, Bodies (human), Plants, Fire, Images/Sensations, Minds (human), Earth, & raw arcane Power). Thus, Creo Ignem spells create fire (and the normal effects of fire, such as heat & light), while Perdo Imaginem spells destroy images and other sensory experiences (e.g. invisibility, inaudibility, making food & drink taste bland, etc.), and Creo Mentem spells can create ideas, memories, and intentions within a person's mind.

Magi have spells they study & learn (called "Formulaic" magic), but can also create new effects on the spur of the moment (called "Spontaneous" magic). Spontaneous magic is less powerful, but much more versatile, than is Formulaic magic. Magic is treated in this game-system as a serious object of study: magi are supposed to spend a long time in their laboratories, preparing new spells and potions, and increasing their knowledge of the Arts. The other main innovation was the insistence on play-acting the characters - indeed, many characteristics of the later Storyteller system developed by White Wolf Games can be traced to Ars Magica (and the fact that both Ars Magica and the Storyteller system were both developed by the same person); White Wolf's Mage: The Ascension was envisioned as "Ars Magica in the Modern World," and many of the changes in Ars Magica's 3rd edition were introduced in order to make the game-worlds more compatible.

Ars Magica is an example of a Troupe System, although a number of Campaigns (known as Sagas) will have most stories run by the same person, known as the Alpha Story Guide.

Originally developed by Jonathan Tweet and Mark Rein-Hagen in the late 1980s, Ars Magica was first published by Lion Rampant games, who also published the 2nd edition of the game. In the early 1990s, rights to Ars Magica were acquired by White Wolf Games, the company Rein-Hagen had in the meantime founded. White Wolf Games published the 3rd edition, which greatly expanded the settings and peripheral rules while leaving the core system intact. White Wolf also published many supplements, detailing specific regions of Europe, or outlining stories that could be played in the original setting. Ars Magica was later sold to Wizards of the Coast, who produced several supplements, but just before publishing a 4th edition sold the rights to Atlas Games. Atlas published the fourth edition and has published new source-books since. The 5th edition is currently (Feb 2004) being playtested.