There are many examples that get rolled out again and again when it comes to gamification. Several of them come from an experiment that Volkswagen did a few years ago called The Fun Theory. Two very popular ones where the Speed Camera Lottery and the Piano Staircase.
The idea behind the staircase was to see if people would use the stairs rather than the escalator next to it. And, unsurprisingly, the number of people using the staircase did increase. Sadly, the experiment didn’t’ last very long, so it was not possible to understand if this was just due to novelty. Also, there are no statistics on how many people’s behaviour was changed to the point they continued to take the stairs after the piano was removed.