Half-Life: Alyx - Hands on with Valve's virtual reality game-changer
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.