The links to the various releases on sigil-ebook.com work quite well for me.
code.google.com is the old home of Sigil of Sigil's source code and binary downloads. Its new home is on github.
The homepage for the Sigil repository on github is
https://github.com/Sigil-Ebook/Sigil
Near the top of that page you'll see four links (3,239 commits, 5 branches, 22 releases, and 16 contributors). The "releases" link will take you to where the various releases can be downloaded (but I honestly can't imagine why the links from the Sigil-ebook.com blog aren't working for you).
A direct link to the "Releases" page on github is
https://github.com/Sigil-Ebook/Sigil/releases
Thanks for telling us that the links in the "
Downloading Sigil" thread were broken. They weren't updated after user_none changed the repository into being "owned" by an organization and turned over the reins. Those links should be fixed now.