When you've been playing a game as long as some of us have been playing World of Warcraft, you get some unusual moments of realization. One of them occurred to me recently, when talking about the upcoming 9th Anniversary of the game this November 23rd. The person I was talking to said "Yeah, my mom showed me how to play, I used to fish for her on her hunter" and it came out that said person was 21 years old, and that she has been playing the game since she was thirteen. She has effectively grown up in Azeroth, at least part time - nearly half of her life has been spent playing this game.
Meanwhile, with each expansion the game has lost some players and gained others - there are people who started playing in Cataclysm and even people who started play this year (I know, I've met quite a few of them) and many of them have no idea how to even go about absorbing all that happened in those nine years. To people who've played all along, it all happened - it's part and parcel of the game, it's history we experienced. But to new players, the sheer volume of it all can be daunting - I've had players comment with disbelief when told about 40 man raiding, who don't really grasp just how many times class mechanics have been changed and revamped and altered. One healer simply couldn't grasp the concept of an out-of-combat resser, a healing character who stood back out of range of boss fights and resurrected people who died over and over again. For me, the trippy part of that conversation was reading a 21 year old relate stories of Molten Core to this newer player and realize they were stories of what she was doing in grammar school.
Of course, for me WoW is a game I discovered in my 30's. My early thirties, come to think of it, and now I'm well out of that decade. So we're all aging, but the proportion of time we spent playing the game is different - for me WoW is just one of many games I've played, and certainly not almost half of my lifespan.