Total Annihilation is a science fiction real-time strategy video game released in September 1997 for Microsoft Windows and Mac OS by Cavedog Entertainment and distributed internationally by GT Interactive. Two expansion packs were released in 1998, The Core Contingency on April 29 and Battle Tactics on July 20, while a medieval-themed spin-off called Total Annihilation: Kingdoms was released on June 25, 1999.