I have noticed that it is possible to find old Ars Magica supplements like Mythic Places or More Mythic Places on various websites, at low prices (less than 10$/£/€).
As these seem to contain interesting story ideas I considered buying them, some of my players having asked for more adventures, and more loot. However I would like to know if all the stats (for PNJs, monsters, rewards...) are compatible with those of the 5th edition?
If it is not from the 5th edition, it is not compatible.
Of course you have a lot of intresting ideas in Mythic Places, but you will need to adapt them to 5th edition.
Search for "Ars MAgica Adventures" on the net. There are quite a few. The ones by Kevin Hassall tend to be really good. Durenmar has quite a few of those, and the saga of CLiffheart (reachable through the eire links of Project: redcap) has an extensive collection of adventures.
The 4th edition adventures are pretty much compatible as well. Festival of the damned, ghoul of saint lazare, faerie stories and a few others.
Thank you very much, you're right, the adventures on Cliffheart site seem quite good, even if described quite shortly.
Those wanting to see them can look there: arsmagica.it/Cliffheart/riso ... Adventures
By the way, is there anywhere some easy method to convert 3th edition stats to 5th edition?