Classic Blunders

Being fans of a lot of older games on this site, I see the term "classic" being bandied around a great deal. I've never been entirely comfortable with this because personally my understanding of the term is a pretty narrow definition that would include relatively few games: but that's just my opinion so I kept my mouth shut. However following Michael Barnes' review of Tales of the Arabian Nights and the discussion that followed I thought it might be interested to delve into the question of what makes a classic, and how we might decide what games should qualify.