YMMV: Ars Magica
- Dork Age: Third Edition was published by White Wolf at the height of The Nineties, and partially integrated into the Back Story of Mage: The Ascension. Accordingly, it shares all the hallmarks of their "Gothic Punk" approach of the time; Infernal plots around every corner, attempts to deconstruct the medieval society and its views, the idea that rationalism and magic were incompatible, darkening or questioning the character of every historical figure on stage, and padded wordcounts with little actual content. This was poorly-received by the playerbase, and when Atlas Games received the license, they broke the game away from the World of Darkness and reversed course at full speed, making Ars Magica once more its own beast.
- More Popular Spin-off: The Old World of Darkness. It's made by the same people and incorporates many of the concepts of Ars Magica, and the WOD and 3rd Edition AM were linked together. The two games have gone their separate ways, however, and while they share concepts like the Tremere and the Order of Hermes (and the owners of the two lines don't fight over ownership of either concept), they're no longer linked.
- Scrappy Mechanic: 3rd Edition attempted to include a "Realm of Reason" (most likely to bring Mythic Europe in line with Mage: The Ascension's backstory), which was based on skepticism and scholarship, and which gave off an aura which mitigated the power of other Realms. This proved highly unpopular, not only because it was paradoxical and inconsistent (for example, Reason's presence in libraries meant that casting spells there was penalised, despite magic always having been portrayed as a scholarly and academic pursuit), but also because applying reason to Mythic Europe should confirm that angels, demons, fairies and magic actually exist; denying them comes off more as delusion rather than reason. 4th Edition did away with "Reason", of course.
- Made even worse when you consider that Hermetic magic embraces that type of idea-evolution; several Bonisagus traditions are founded on the very concept of adding new ideas to Bonisagus' theory.