Look, roleplay means a lot of things. What it comes down to though is this: you have a character; that character has wants, feelings, mannerisms, ideas, a history, and of course, attributes. The attributes are visible things, your characters appearance, and your character's stats, things encompassed by the game mechanics; these are a part of roleplay too!
The use of stats in roleplay always seems to be an issue... so I want to clarify a bit how this
should work when the game is further along in development (it doesn't work this way now, and I'm not sure if it reasonably could, but it would be nice to try).
When you start the game, your character has low stats. What this means is that, contrary to what many do, you should not jump into the game as a master swordsman (or swordswoman... though for convenience sake, I'm sticking to the swordsman example). However, you
can be aspiring to become a master swordsman, working on swordplay (killing things)
while maintaining the other aspects of your character. Your stats are limiting to some extent... right now the game isn't really a full game, but when it is, you can not roleplay without regard to stats (and it would be nice if you kept them in mind now). That said, you can not play the game solely for stats without regard to roleplay. There is a necessary balance.
You see, that's the important part: that your character is multidimensional. You can't
just kill monsters. Why not? Your character has wants and feelings and I doubt those are confined to killing things. One of these wants may be to become a master swordsman... but say your character really values his friends. If one of your character's friends asks for help, he'll probably stop killing things and go help his friend. These two aspects, wants and feelings, dictate your character's actions in any situation he may find himself. As you're playing the game, think what would my character do? Is this action in line with his personality?
Mannerisms: this is how your character interacts with people. Does he speak very formally (thees, thys, thous, etc)? Or maybe he speaks very informally (contractions, abbreviations, crude language--careful with this, there are little kids playing this game)? Maybe he has a certain thing he does when he's thinking (/me rubs his chin)? All of these things make your interactions more real and interesting. Mannerism usually comes from history, though your character can of course acquire new mannerisms over time.
Speaking of history... history serves primarily two roles: one, it gives your character a background: what did he do before now? As you play you add to your history; two, it can be a source of your character's wants/feelings. The most basic example: your character hates bandits because his father was killed by a bunch of them on the road. A little more sophisticated: your character fell from a tree when he was young and broke an arm; now he's afraid of heights.
Well, I didn't originally intend to lecture on roleplay with this post... but it seems that's what I've done. :\ Sorry for the long post! I hope you read it all and think when you roleplay. Remember, you control a character. You should play the game with his/her personality in mind at all times! That's the challenge, and the fun!
EDIT: If you aren't seeing the relevance of what I said to the thread... the point is that roleplay is not about what you as a person want for your character. It's about how your character would react when placed in a given situation. If someone's character does something
you don't like... well, live with it or log off, but don't ruin it for everyone else. Now if someone's character does something
your character doesn't like, then your character can react appropriately. The point is, though: you don't control roleplay, you're a part of it. Keep your character true to his/her personality (you need to have a good idea of what your character's personality is!) and the rest will flow from there.
EDIT2: clarified, typos, etc
