...men aldrig riktigt fått klarhet i hur man spelar det...
This in a nutshell is something the people behind Ars Magica has never managed to explain
When playing tabletop Ars, it's much like any other mystery/investigation game where players work together to find what is causing a problem and then decide how to fix it and do it. A game like Vaesen probably owes a lot to Ars.
Ars Magica comes from a view that "RPG rules should simulate the physical effects of actions in a fictional universe", anything about story or drama comes from the players. I would never play Ars Magica with the rules-as-written today.
Three things I liked and still like about Ars Magica: Troupe play, Mythic Europe, and Order of Hermes.
Troupe play: Rotating game masters and shared cast of characters.
Mythic Europe: The world we play in is medieval Europe but like how people thought it was. Dragons, faeries, demons are real. You can encounter historic characters and change history.
Order of Hermes: Wizards -- gifted, powerful humans -- live in a parallel world with their own set of rules trying to prevent all the other powers in the world to unite against them.