What about dice?
Dice can be used in some RPGs, but really it's up to the GM's discretion. I've found that most online RPGs don't use dice, but if you would like to, you can, provided that you have your own set.
I personally own a full set of Dungeons and Dragons dice(and I'm not ashamed to admit it, either), but I still prefer not to use them. That way, it gives the OP or GM more control over the outcome of a game. I don't like the element of luck in a game, really. If a player makes a stupid mistake and you're on dice, you could roll a perfect 20 and they would win; if they make a brilliant plan and you roll a 0, they're **** out of luck. With the non-dice games, luck is taken out of the equation and the player is rewarded or punished based solely on how they play, and not on something that they have no control over.
Or at least, that's my take on the matter. You're free to draw your own conclusions.