In 1998, Half Life changed first-person shooters forever.
It combined cinematic storytelling, taut and tense combat and extra-dimensional bad guys.
A successful sequel followed, but it’s been nearly 13 years since the last release.
Now the series has returned in the form of a virtual reality title.
BBC Click’s Marc Cieslak was one of the first people in the world to play it, and he suggests it could be VR’s first killer app.
See more at Click’s website and @BBCClick