My best gaming moments have all been in MMOs
You have to remember everything gets a little more personal and a little more important. It elevates the game to a higher level of importance which means the personal gain for reaching goals in itis so much higher. Getting new stuff becomes a bigger reward .. Beating people in PVP becomes a bigger reward - and so on.
I've spent most of my MMORPG time in the norwegian game Anarchy Online which launched in 2001. It was my first MMORPG and playing it after release was just incredible. It was tough as hell, it really beat us up and it took about a year to really get into the game mechanics as it's ridiculously advanced and there's so much to learn. It's easier now that there's money in the system and people know their way around, but back then, everyone was piss poor starting out in a horribly hard game.
Although there are plenty of people who play more than I do, I really had a life in there - or rather, a few. At first, I approached it very much like a pen and paper roleplaying game and so did my friends.
That's the city Tir in the screenshot. When we started out, we had a beggar's guild in this city and our aim was to know everything about everyone, including intelligence. We would actually spend hours running and dodging dangerous wilderness to get down to omni-1, the enemy city (although there was a fragile sort of peace between the two factions back then). We reported back to other guild leaders and actually had a longer running mission about finding out about this omnitek employee who was creating something of a cult .. hm!
Sometime later, we had made some money and started the Tir City Watch. We had red uniforms, patrolled the streets and helped out newbies. We had quite a few recruits that we put through training, like finding eachother by coordinates out in the wilderness or crossing the Mort desert, which was full of dangerous monsters, on foot.
After an expansion which allowed for land control, we started a new guild, Clan Imperialist Army where we played warmongers who tried to unite the clans against the omnitek faction. Every week, a whole bunch of clan leaders came together and discussed to figure out how to best beat our enemy. I've had more political speeches in that game than I have spoken or presented anything in real life which is actually quite a bit.
There's plenty more to tell about all the time spent in other guilds and other friends, but my point is Anarchy Online was more than just a game to me and my friends, for better or worse. We had lives in there and playing it was incredibly rewarding. It's just a bit sad and perhaps a bit spooky that none of those rewards really last.
edit :
I don't play MMORPGs at the moment by the way. It's still fun, but the pioneering spirit and the marvel of playing in a world which was incredibly huge like you could never explore it all, was just magnificent and I haven't really felt it since 2001/2002. Anarchy Online had a lot of computer generated landscape - tons of it. It is much bigger than any other MMORPG I've played, including World of Warcraft. The quality of the nature is less, but it gave it a great sense of realness. Playing in such a world for the first time was really special to me.