A 1998 first-person shooter that blends immersive storytelling and physics-driven combat as scientist Gordon Freeman fights through the Black Mesa Research Facility after a catastrophic experiment.
- Developer: Valve
- Genre: First-person shooter
- Platforms: PC (1998); later PS2; community remakes and updates (e.g., Black Mesa)
- Mechanics: Seamless level progression without cutscenes, environmental puzzles, varied enemy AI (HECU, Xen creatures), physics interactions
- Notable: Critically acclaimed narrative integration, influential design on scripted sequences, foundation for the Half-Life series and mods (Counter-Strike)