Some veterans of reading untranslated VNs refer to the period between 2004 and 2010 as 'The Golden Age of Visual Novels'.  However, you shouldn't really take that statement at face value, as the meaning is a bit more complex than you'd think. There are some significant differences between VNs today and VNs during that period that both made it the peak of the medium's sales in Japan and produced the greatest ratio of quality VNs to crap VNs.  One of the primary differences was that, oth