Total Annihilation is a real-time strategy video game created by Cavedog Entertainment, a sub-division of Humongous Entertainment, and released on September 30, 1997 by GT Interactive for Microsoft Windows and Mac OS. It was the first real-time strategy game to feature 3D units and terrain. Two expansion packs were released, The Core Contingency on April 30, 1998 and Battle Tactics on June 30, 1998. After the closure of the Cavedog Entertainment Studios in 1999, the intellectual property fell to Infogrames (now Atari).