Huge linear world, in which you need to avoid ennemies and make your way through the end, with some puzzles and a lot of walking just gazing at the landscapes.
The world is both beautiful and creepy at times. A nice experience overall, Reached the end in 5.4 hours, but I didn't get all the achievements, so it can be longer if you want to complete it 100%. I must say that even if I enjoyed the experience, I'm too lazy to go back for those I missed ^^;