What determines where adventure sites are? Do I just choose where they are before the session?
On the Forbidden Lands map, Villages, Castles and Dungeons are marked. On the map there are also a terrain type called Ruins. That is just a terrain type, but can also act as an adventure site if you like (can be anything).
What is it the player's do at an adventure site? Unlike MYZ there's nothing specific for them to do (e.g., get supplies for the ark).
In the official adventure sites, you have, well adventures. In the GM's Guide, you have three of the official adventure sites, one of each type.
- In 'The Hollow', we have a Village where the players find several intrigues that they can help solve, one way of the other, there is also the fact that some ghosts wander about at night.
- In 'Weatherstone' we have an old Castle that that has a curse upon it, but also legends about treasure.
- In 'The Vale of the Dead', the players find a Dungeon filled with things to discover.
If you use the rules to create your own adventure site, those sites will have their stories to be unfold by the players and if you don't have time to prepare adventure sites yourself, then there is the campaign book (Raven's Purge) with nine adventure sites linked together to a campaign) and also an adventure book (Spire of Quetzel) with four independent adventure sites. All these sites, including those that you create yourself, can be placed on the map on the various adventure sites hexes as you see fit.
In the campaign (Raven's Purge) there is an epic story that drives the players. If you don't play that, then it is up to the players to determine what drives them to do what they do. Perhaps they like to have a Stronghold and that cost a lot.