Maprunners is the retirement project of a fella in Brisbane. It has similarities to the app "Turf", in that you have to go to points on your map on the phone, but there's nothing actually on the ground.
A map is uploaded and a course planned, this is then downloaded onto your phone. All you need to do then is take your phone to the location of the checkpoint on the map and it will register you've been there! No need for physical checkpoints ever again!