When you click g3.php or 28.php, it checks to see if you have a valid crc and o cookie, if not:
You will be redirected to the captcha.
The captcha consists of a text instruction and a captioned SVG
It will say something like:
Enter the last 3 characters)
(4 8j 2)
Here, the solution is 8j2, not 48j2.
You can enter a name, change the colour, and set the minimum refresh delay
Click "Enter with Audio" if you want the chat to try pinging you when it gets messages
(Otherwise, click "Enter without Audio")
Once you enter, JS will try to select the message box for you, you can read and write messages as you wish, pressing send to put them into chat
You can also click edit or delete on messages you have written if you still have valid cookies*
Clicking Reply will allow you to send a quoted reply.
*Note that after 9 or 10 hours, or if cookies are cleared, edit and delete will fail.