This is really fun, I love it. One could devise a whole game around that. Define functions that give you coordinates on a sphere (in this case, the earth), wher

This is really fun, I love it. One could devise a whole game around that. Define functions that give you coordinates on a sphere (in this case, the earth), where X (e.g. the "treasure") is hidden. Then plot the functions, make k shares and make them (and mod p) discoverable through different other games (e.g. programming challenges). Then the first person to win all k-1 challenges and mod p is able to interpolate the exact location of the "treasure". A wonderful mix of maths, programming and real world adventure.