Spoiler alert I guess for people wanting to find the stones all by themselves...
I can only join in the praise. Lovely design and very functional game play so far. Only thing that threw me off is that I lost my entire days work because the game got stuck when I dug up the keystone in the Dig Site and then opened the inventoty. First time I did not think to much about it however it happend again a second time when I redid that day. Digging up another keystone I did not have this problem. No hard feelings, I only cried a little bit. ;)