I'm Chris from MandelDuck, I created a couple of bitcoin tipping games on iOS called SaruTobi and Game of Birds.
We have just finished testing a bitcoin geocaching game called "takara" The app lets user drop bitcoin tips anywhere in the world however collectors must visit a location where bitcoin has been dropped to pick it up.
We plan to launch soon as beta testing has finished.
You can checkout a demo video of the app here https://www.youtube.com/watch?v=gpGK1JozTio
Our basic idea is to get people engaged in bitcoin via gaming as it is zero risk and requires no exchange registration, KYC ect
If you have any questions/criticisms or ideas I would be happy to answer them!