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 operating systems. Sins of a Solar Empire is a real-time strategy (RTS) game that incorporates some elements from 4X strategy games; promotional materials describe it as "RT4X." The game was released on February 4, 2008, its first content expansion, titled Entrenchment, was released as a download on February 25, 2009, and its second content expansion, titled Diplomacy, was released as a download on February 9, 2010. A package combining the original game with the first two expansions was released at that time with the name Sins of a Solar Empire: Trinity. A third expansion, stand-alone Rebellion, was released in June 2012.