Trying to avoid spoilers, the basic idea(s) are very good. Other substories around the basic story (historic but as well as personal moments) are also very good and touching. The slow, eerie atmosphere adds also to the experience. But... I think it lacked that little extra care and touch while its pace (slow) felt forced to create another 2-3 seasons.
My view on the episodes:
1st: very good, hooked me to the series
2nd: good helped progress the story, too much emphasis on the game
3rd: very good, further improves, but too much of the game
4rth: good but could be better
5th: Well, it was very good, but I think that the reason it has the best rating is that it has some good visual FX
6-8: they are all good, but the problem is the blend. While I value very much the human moments and perspective, I think that they lose much time on them, they could consume half the time of them without loss of character depth and use it to progress the story or have something more interesting to fill the time.
Generally I felt that it could be something brilliant.but in the way it lost its potential because I felt they stretched all scenes to make additional episodes.