Off topic: The sentinel seems to be a very interesting game by Geoff Crammond (Stunt car racer).
All I remember from back then is that I didnt understand the gameplay
I will give it a shot as soon there is time.
What I just found out:
You have to rise your position on the map (which costs energy) but can gain energy from objects like trees. And the sentinel (slowly turning) may not see you or he drains your energy. When you reach a higher position than him, you can take his place and win the map.