Gordon Freeman, male protagonist, HEV suit, crowbar, physics-based puzzles, City 17, dystopian environment, Combine soldiers, headcrab zombies, resistance fighters, Alyx Vance, sidekick, urban decay textures, concrete structures, rusted metals, atmospheric lighting, dynamic shadows, first-person perspective, action pose, detailed facial expressions, sci-fi weaponry, gravity gun, immersive world, interactive objects, high-resolution textures, panoramic view, dramatic lighting, advanced physics engine, realistic materials, Valve's Source engine.