Legend of Krystal Forums

Okay so, i request that if possible, when a computer connects to "http://www.legendofkrystal.com/forum" or any other sub folder of it, that the computer gets a warning message basically saying this is an adult site. Maybe if they don't have a cookie on their computer.
I have a project that i'm trying to start up and one of the things i'd like to do is link to the LOK forums, but i don't dare link to the forums because there is no warning message. I am willing to link to the main page http://www.legendofkrystal.com which has the 18+ warning; however, if i want to link the person to forum thread or post, then i can't because i'm limited to the front page.

Don't know if this is really possible.

(1 month later)
Actually, this is not a bug problem, but a lack of PHPBB support, but either way...

I agree. I'm also researching on. I dont like to do it manually (pg->connect funcions , session variables and such in a page like xxxwarning.php), because its not recommended (although possible if I dont find a more MOD'able way). Neither on PHPBB MOD site:
https://www.phpbb.com/customise/db/find ... ds_adult-c

And no, just icons like '18+' circle is not enough :/
There are non-phpbb alternatives (an alert screen) like This one

Renara can also use to password protect XXX forums and put the password in the description in red color.
So, by entering this password you are agreeing you are 18 years old or older.

And we can use a quick approach. Make the 18+ forums (like Board Index->Creative Corner->XXX Flash games) forcing you to log in, with a message on the top:
'The board requires you to be registered and logged in to view this forum.'