From BoardGameGeek.com...
This second expansion for Race for the Galaxy delves into the growing conflict between the Rebel and Imperium forces. This expansion increases player interaction by adding takeover rules that allow players to conquer military worlds in other players' tableaus. This expansion also includes, among the new cards added, two player-submitted cards.

Requires Race for the Galaxy to play. Race for the Galaxy: The Gathering Storm expansion is optional, but recommended and adds solo play. With only Race for the Galaxy: Rebel vs Imperium, min players is 2 and max players is 5. Both expansions are required for 6-player games.

From Rio Grande...
As the Imperium crushes outlying systems, Rebel worlds begin to ally,politically and militarily. Meanwhile, the Uplift Code, within the genomes of the Alien Overlords� former servitor races, is being sequenced.Can you build the most prosperous and powerful space empire in a galaxy where border conflicts rage?