Since mid 2010, KIA Invisible Agents has been an invitation only website due to a deluge of spam registration clogging up the normal workings of the site. Since that time an existing agent has had to send an invite to a potential new operative before they could register.
These invites can also come in the form of ‘invitation codes’ that you can use on the registration page. You can use ‘Chemical Serpents’ or ‘Kaos Hieroglyphica’ as invitation codes, even if you don’t have copies of the books. 😉