This game is a gem used in the Boy Scouts to teach orienteering - this skill of using a compass to navigate. You set up 10 stakes spaced at 10 foot intervals, there are several cards that you give to each team and it has a direction and distance of 3 legs. Each team starts at one stake and navigates to the final stake. You get points for how close you are. the length of the game depends mostly on how flat the terrain is. It could take only 60 minutes or even two hours, but most seem to take about 90 minutes from what I remember.