Hunt for the treasure
Hide a series of Flics somewhere (the garden, the living room, the nearest IKEA store) and get people to press them in the right order to win. Could be expanded geocaching style - the earth's the limit (for now)!
Per Hård af Segerstad commented
To clarify: when a Flic is pressed a map/clue to find the next one is displayed, either on someone's smartphone or on a screen nearby.