
I've played Achaea, Nationstates, Cantr, <i>and</i> Runescape but never Particracy
Achaea was fun for a while. I got a character to a level in the lower thirties once and two or three more I brought to the lower twenties, but in order to become really powerful you needed to buy uber-expensive credits and that kind of ended my enthusiasm for it...
I played Runescape for longer...I've got a char with around 1210 total levels in it but I don't really like paying $5 a month for a game when there are so many awesome free games out there so I've pretty much quit it...
I've been playing Nationstates for a couple of years. I've got five nations with populations ranging from 2.1-4.2 billion people each, all within the same region. We had three people playing it for quite a while but the other two have just recently had all their multis deleted

It's sad. I, myself, only log on often enough to make sure none of my nations get deleted because there's always been so much inactivity within the region. My region is called DeKalb.
Then I've been playing Cantr since the beginning of February. I've also played a lot of other games but those are the only ones that have been mentioned in this post.