A beautiful environment and nice story-telling.
The game-mechanic of you movement is also pretty cool and innovative. Just guess without the video I would not have got it^^ Just walked around and wondered why everybody is doing this hand gesture :-D
I also tried to climb this ladder on the right. But even after hours in Population: One, i somehow couldn't go to the top. As i watched the video, saw, that it was just the wrong way. Maybe you could make it a bit more clear or so. Same for the letter-placement at the hand.
Also, like others said already, somehow i felt bit too "small" for my virtual body. And whished there was a way to rotate.
But i enjoyed it all in all, especially the whole mood and soundeffects (e.g. the wind the higher you go). Guess with some polishing and new tasks and so it could become a nice game.