Gentoo Prefix
The youngest member of Gentoo/Alt is the Gentoo Prefix project. It emerged from the Gentoo for Mac OS X project, which suffered from multiple practical problems initially. It allows installation on MacOS X, Solaris, FreeBSD as well other Linux distributions. The core principle of Gentoo Prefix is that installation of packages by Portage are done in an offset, thereby leaving the host OS unmodified. As a side effect, administrative privileges are not required.
Read more about this topic: Gentoo/Alt