The presented thermodynamic landscape of HCN-derived materials has several consequences for interpreting HCN's reactivity in various astrochemical environments, in and beyond the solar system. Most (but not all) previously proposed HCN-derived polymers and molecules can form spontaneously (ΔGr<0) at close to Earth ambient conditions. In low-temperature environments, like those on Titan, the entropic penalty for making larger molecules and polymers (-TΔS) naturally decreases. In other words, the chances for thermodynamic spontaneity of macromolecular formation increases in cold environments.