Just finished watching it in about 3 days..

stopping in between is incredibly hard. My experience was that I had to stop for a few hours after every 7 episodes or something to let it all sink in. Up until the last episode I thought that it would end the 'it was just a computergame' way, with all the kids waking up in the cave or something.. I couldn't believe that it all really happened. But it did . the final episode ended great. No miracles or anything. I'd love an additional series or OVA that explains the loose ends discussed above.