Both Drew and I are big into getting aspects of a treasure hunt into our next game… Crackdown did a fantastic job of giving you that sense of seeing a goal but not allowing you to get there untill your character can jump just a little bit higher. There is nothing quite like that feeling of unlocking a skill and using it to get a treasure that you saw ages ago but could not get. The longer you have to wait to get a treasure the more exciting it is when you finally get to have it. There is a point of course where it takes too long and you forget about it. But finding just the right balance is key to making the system work.