Rock-solid security above all else.
Granite is a hardened variant of Linux meant to be used as a single-purpose virtual machine image for security sensitive applications.
Granite aims to be as secure as possible at the expense of performance, usability, maintainability, uptime, etc.
Nothing is set in stone yet. Granite is currently in the design phase: things will change often, things will break often, pull requests welcome!
Granite is based on Gentoo Hardened and utilizes Packer to build virtual-machine images.
Because it isn't paranoia if they're really out to get you.