A few years before the events occurred in the Black Mesa Research Facility, Gordon Freeman gets reanimated. Soon enough, he finds his world invaded by aliens. Join the resistance forces to find a way through this mess and reclaim your home!
- Developers: Valve Corporation
- Publishers: Valve Corporation
- Initial release date: 2004
- Platforms: Microsoft Windows, Xbox, Xbox 360, PlayStation 3, OS X, Linux, Android
- License: Commercial