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Not that I'm experienced with the real life sport but this seems like a very faithful rendition of Orienteering.
The attention to audio makes the experience a lot more immersive. You've captured the feeling of getting lost in this game better than any other I've played. A little work to make the worlds a little colorful/varied/lively and you'd really have something special here. Well done!
One twist/suggestion: Caves! Just a thought. ;)
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This would be even better if you made a little introductory course that would teach basic map and compass skills. Excellent orienteering game!