Cinematic 8k wallpaper featuring a colossal Cthulhu towering near a lighthouse perched on a mossy rock amidst a violently stormy sea, captured with sharp focus. The scene is imbued with megalophobia, showcasing an extremely detailed 4k digital painting that boasts a subtle organic glow. This photorealistic composition radiates cinematic, movie-quality aesthetics with a dark, moody atmosphere. Lumen reflections dance gracefully across the water, enhancing the atmospheric lighting and subsurface scattering to achieve hyperrealism. The image is insanely detailed, resembling a highly realistic photo captured in 64k UHD clarity, with precision akin to a DSLR camera. Developed using Unreal Engine 5 and Octane Render techniques in 8k resolution, the scene is subtly altered to include soft bioluminescent accents on the Cthulhu, which contrast mesmerizingly against the tumultuous waves and create a captivating, immersive visual experience.