I walked around, collecting bottles. I guess this is what the game is about.But then I suddenly found a place beteew to "rooms" that made it possible to grind. Walk from one room to another, collect bottle, walk back again, more bottles in the same room I had taken all seconds before, walk back, even more bottles in the room that was empty before. I lost the interest to explore, when I could just grind the bottles between these two rooms... So, maybe a bug?