Together with a friend I made up a little mystery/puzzle game as a wedding gift for two friends back from school. It was a series of questions and insiders about the last ~17 years that we knew each other, seperated by all the places where we have been together. They had to fill out the awnsers into a crossword puzzle, then derive some numbers, do some math to get a number combination for a padlock to open a travel first aid kit (for the honeymoon and so on) with money added. They did very well!