Retribution is the final expansion for Galactic Civilizations III. Gal Civ 3 - Retributibution features powerful artifacts buried on planets across the galaxy, hypergates for faster travel, the Drath and Korath civilizations, cargo ships and a new technology tree.
Galactic Civilizations III: Retribution System Requirements
PC System Analysis For Galactic Civilizations III: Retribution Requirements
A mid ranged PC can run Gal Civ 3. To get reasonable frame rates you will likely want an Nvidia GTX 460 or better graphics card. A more powerful CPU will help resolve the CPU turns more quickly in the later stages of Galactic Civ III. Add at least 6GB of system memory to get the best performance.