The party finds a small box that will only open in one specific location in your campaign world. When the party tries to open it anywhere else, a ghostly face appears over the lid and tells the party that the chest may only be opened in a location x leagues, miles or feet away. It will then say a number before it disappears, which starts at 20 and counts down each time they attempt to open it.
The players may attempt to open the chest only 20 times. On the 21st attempt, it will teleport back to where it was found (50% chance) or to the spot where it can be opened (50% chance). Attempting to open it with a wish spell will have the same effect. Lesser spells have no effect.
This was inspired by a real product, that uses a GPS-based lock that will only open in one location on earth. Be sure to read the article to see how the recipient managed to solve the puzzle. It shouldn’t take anywhere near 20 tries, unless you place the special spot underground.
I saw this at the Maker Faire in New York.
Very clever, it turns a treasure in a quest and is more fun than a treasure map. But I think having the voice give cryptic clues would be more fun than just X distance (which is very modern). Also, the characters could research the style of the box, which might give you additional clues about where the box should be taken.
I think those are also great ideas.
I am wary myself about clues because I am terrible at finding that balance between obvious and unhelpful that makes for a good puzzle. I’m more likely to see if they figure out how to get there (and not everyone will know how to triangulate) but place the secret spot somewhere surrounded by DANGER.
Of course if I do use this in a game I’ll probably have to do what you say, since I’ve blogged this.