A vibrant, high-quality 16-bit retro pixel art scene depicting exactly one small, heroic white cat defeating a massive, fearsome fantasy dragon. The heroic cat stands upright on its hind legs in the center, striking a dynamic victory pose. It wears a tiny, glowing blue hero's cape. Its front paw is raised high, pointing a glowing, pixelated magic sword upward toward the sky. The cat's anatomy is perfectly rendered in clear, clean pixel clusters, with distinct four limbs and no messy distortion. Above the cat, a gigantic green dragon has just been defeated; its red HP bar at the top of the screen is completely empty at 0%. The dragon dramatically falls backward into colorful pixelated explosions, particles, and bright yellow smoke, clearly visualizing its defeat. The background is a classic side-scrolling RPG boss stage set inside a dark, ancient stone castle dungeon, with glowing torches lining the walls. The entire image has a crisp, authentic video game aesthetic, featuring a limited retro color palette, clear pixel grids, and no smooth gradients. This is a beautiful 16-bit video game screenshot, with highly detailed pixel art and sharp details.