The reason for that (and for almost any page not allowing children under 13) is COPPA (the Children's Online Privacy Protection act) - which requires whoever has a website to obtain parental permission if they know they "store or share" information from a child younger than 13.
Since chatting does count as "sharing" information (you're saying something in chat, and the game shows it to the other person, so I just shared what you said with them), and since sending a mail does count as "storing" information (if you send someone a mail, I need to store that in the database until the other person picks it up, so I can show the other person the mail), it applies to this site as well.
And since you just said yourself you're 10, I obviously know you're younger than 13. ;P
COPPA is US law, so I also obviously have to follow it.
So, that's the back story. Now, I don't kick out people immediately, but I still need to get the permission form, since I know you're not 13, and if I keep "storing and sharing" information, I would violate US law. What I do is when I know someone's not 13 yet, I stop "storing and sharing" information immediately (disable chat / forum posts / mail / etc), and check the past forum posts for personal information. If I don't receive the form within some time, I delete them entirely, so I don't get in trouble.
Hope that shed some light on this. What you need to do, though:
- Ask your parents if it's OK if you play this game (and chat with other people on the internet).
- If they're OK with it, they need to tell me - I have a permission form (you'll see it in your in-game mail) that they need to fill out and return to me. On the form, I ask for some contact info from your parents, so I can contact them if there's any trouble (and likewise they get my contact info, so they can contact me).
- Once I receive the form, I save it form securely, and re-enable chat/mail/whatever your parents allow you to do.
