media-libs/libkface-3.3.0 bundles OpenTLD (not in tree yet) https://github.com/gnebehay/OpenTLD/releases (yes this seems to be the main repo, the owner is the main author and author of the corresponding thesis)
OpenTLD now packaged in dilfridge overlay, with a hack to get a shared lib. Not sure if we will ever need it, because of https://bugs.kde.org/show_bug.cgi?id=324566 Copied code is license-incompatible (OpenTLD is GPL-3, libkface is GPL-2)
this is fixed in the 4.x series.