two characters, Chell and Atlas, cooperative gameplay, split-screen view, Portal 2 environment, advanced portal gun, futuristic white laboratory, complex puzzles, companion cubes, energy balls, laser beams, portalable surfaces, blue and orange portals, robotic gestures, dynamic duo, teamwork action, high-tech panels, Aperture Science facility, interactive gadgets, LED lights, metallic textures, clean design, soft ambient lighting, wide-angle shot, detailed background, science fiction theme.