All you guys tired of MMOs or feeling too old for them should just play
Kingdom of Loathing. It's more of a turn-based browser RPG, but fun, funny and free to play - although getting the store items makes life a little easier, of course. It's possible to buy those with meat you made or farmed in-game, though (uh, meat is the game's currency), so it's not necessary to give money to the game if you don't want to. I still do, because it's awesome. I've been playing for over four years now and am still not bored.
Since it's turn-based it's really more of a single-player, but there are leaderboards for competitive players and clan basement dungeons you can do with your clannies (or on your own if you're a misanthrope). Chat is text only and you can choose which channels you listen to - just your clan if you decide to join one, or just the open chat channels, or both - so you won't have to deal with ranting 14 year olds (you'll get the occasional "auuugh this stupid game" text-rant from 30 year olds though). There's even a literacy test to pass before you can enter the chat, hehe. Um, I mean, it's a very difficult test! :|
The community is great and (mostly) super helpful, and you can pretty much choose your playstyle and how much time you want to spend on the game, since you only have a limited amount of turns every day (which can be increased by eating and boozing). It looks silly and lighthearted with the stick-figure art and bad to brilliant puns, but we have a lot of die-hard spreadsheeters, speeders and serious spaders who spend a TON of time on the game, and the mechanics are pretty intricate if you get to that level. But if RL or a bit of burn-out gets in the way or you're just not in the mood you can let it rest for a while, do a slower run or two (you can replay the game as different classes, but perm skills and keep your shinies) or just hang out in chat, work on trophies or do lazy PVP or whatever. There are lots of possible achievements.
It's the only kind-of-MMO I play, because I like the independence I have as to when and how I achieve something while still being part of a community with similar goals. Things like male teenage chest-beating, decreasing reaction time or constant dedication are not a factor, and the community is more mature and accepting than others. Also stupid jokes ftw.