Guild Wars 2

Players could randomly find a “drop” on a random mob, such as a message in a bottle, or crudely written note.

“Using” that note puts the player on an event.

Basically, this is like the “book” Halloween treasure hunt, but isn’t seasonal dependant.

It’s random is to whether the player finds the initial bit to set them going. And until they get that, they cannot proceed to the next bit. And just like the Halloween activity, the tooltip for the item gives a hint.

If there were multiple “treasure hunts”, which all can pick from a bunch of different locations to form an event chain, then this would ensure a measure of dynamic feeling is maintained with the activity.

Of course, there could be a decent reward when it has been completed (such as karma, money and/or loot).

Perhaps some could only have their final stages completed in dungeons? Thus there could be objects inside the dungeons that are only interactable if a player just happens to be at the stage where they need to find it.

I think this is a good idea but may not work if the loot rewards are as poor as they currently are setup in the game for other chests and boss drops.