Hi,
Apparently your password is required to login with your username from now on:
NO COW: Bad name or password: guesting...
Message from GameServ: Login failed. Unknown username or password. You can play as a guest, or try to log in again. You can register for free on http //forum.thudguld.com
Thudguld? 
OB.
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Guld? Yes, it's an old uberwald word, meaning "game". Thanks, fixed the link
And yup, passwords are needed. Next step is allow you to log in automatically if you're logged into the forums, or have a forum cookie. Trouble is, the cookies are for a single domain, so making that work could be "fun", for some small or negative value of fun.