Meanwhile, the monsters scuttle about unseen: you hear them in the ducts and behind locked doors you see the eviscerated bodies of your workmates.

From here, you stagger through a series of sequences that work like disaster-movie scenes: pockets of survivors – gravely injured scientists, desperate security guards – drip-feed you information, drawing you further into the plot. Freeman, weak and disorientated, must grab whatever he can to survive and the game’s first and most iconic weapon, a crowbar, symbolises your role as a worker rather than a soldier. The game progresses not as a power fantasy, but a survival story. ‘You can stand and listen, or just wander off’ … Half-Life gameplay. From then on, your job is to get him out of there alive. Freeman regains consciousness to find the lab both collapsing and full of hideous HR Giger-esque alien monsters. The lab experiment turns out to be a disaster beyond imagining: it opens up a fateful rift in space-time, unleashing the massive explosion you’ve been waiting for. The message is simple: you’re trapped here too. The lack of cinematic cutaway scenes showed great faith in the world and the player, and deepened your relationship with the environment and the protagonist. In this way, Half-Life is naturalistic, which was a revelation in 1998. You can stand and listen or just wander off. As you enter the facility, fellow scientists chat to Freeman about a forthcoming experiment, voicing concerns and discussing trivial details. The opening accustoms us to the Black Mesa research facility, tells us a little about Freeman’s role and sets up the narrative universe – all without leaving his perspective. The brilliance of Half-Life begins with its immersive storytelling. It was the first hint that this new game from fledgling Seattle-based developer Valve was going to be something interesting and unusual. In the background, a computerised female voice issues safety information, while through the windows we see tableaux of life at the institution: weird robotic machines, bespectacled scientists, a security guard desperately banging on a sealed door. A monorail carriage slowly transports everyman scientist Gordon Freeman to his new job at a remote science facility, Black Mesa. M ost action video games begin with an explosion.

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