Human Rebels, Vortigaunt Rebels. The Combine ( / ˈkɒmbaɪn / KOM-byne) are a fictional multidimensional empire which serve as the primary antagonistic force in the 2004 video game Half-Life 2 and its subsequent episodes developed and published by Valve Corporation. The Combine consist of organic, synthetic, and heavily mechanized elements.mF4aBd.