Sadly its invite only and I know nobody with an invite. If anyone fancies throwing one my way it'd be appreciated.
You (and anyone else) are welcome to email me for an invite. It's not intended to be difficult to get one, I just want to keep it under control and avoid any giant floods of users/bots.
Please read the announcement post for some general info about the site's goals, and the info for requesting an invite is in there: https://blog.tildes.net/announcing-tildes