Sins of a Solar Empire is a science fiction real-time strategy computer game developed by Ironclad Games and published by Stardock Entertainment for Microsoft Windows computers. The game was released on February 4, 2008, and its first content expansion titled Entrenchment was released as a download on February 25, 2009. Sins is a real-time strategy (RTS) game that incorporates some elements from 4X strategy games; promotional materials describe it as "RT4X.

Sins of a Solar Empire is a space-bound game. The playing field is a 3D web of planets and other celestial objects in the orbital plane of one or more stars. It features a sandbox mode, allowing the player to choose different types of solar systems to unlock achievements. Players can conquer neighboring planets and explore distant star systems in a "massively scaled, fully 3D environment featuring entire galaxies, orbiting planets, clusters of asteroids, space dust and radiant stars." Notably, there is no single-player campaign mode, but games can be played against AI opponents offline and other players online. Ironclad Director Blair Fraser asserted that the game's "Iron engine" is specially designed with new technologies that allow it to handle very large differences in size, scale, and distance

The game was awarded the title "Best Strategy Game of the Year 2008" by X-Play and GameTrailers, and the title "Best PC Game of the Year" by IGN.