The game was a co-development between Microsoft Game Studios and Resident Evil: Operation Raccoon City studio Slant Six Games, which made the title's movie sequences.
In Galactic Reign, players and their opponents will colonize planets, design ships, and build fleets as they fight to control the galaxy.
Microsoft says ship design is "crucial," as players must predict what their opponent is building and design a model to counter it.
Battle sequences are rendered in the cloud, Microsoft said, showing results through cinematic movie sequences. Players can take turns whenever they like, with the game advancing once both sides have submitted their actions.
In addition to a head-to-head mode, Galactic Reign features a range of single-player missions.
A Galactic Reign trial, which includes one game species, is available to download for free. Players can unlock all three species through an additional $5 purchase. Galactic Reign also includes Xbox Live achievements and multiple leaderboards.