It looks like the page header/navigation got lost in time. Archive.org shows a lot of now-missing content [1], perhaps in the move to GitHub Pages?

In any case the download page does still exist: http://mentat.za.net/supreme/download.shtml

Which leads to the repo: https://github.com/stefanv/supreme

[1] https://web.archive.org/web/20140204102520/http://mentat.za....