research icon, clicking hand, technology tree, World War II era, military equipment, tanks, planes, ships, infantry, artillery, doctrines, real-time strategy game, Hearts of Iron IV, detailed UI, historical focus, global map, dynamic lighting, strategic zoom, in-game screenshot, user interface, interactive elements, highlighted selection, immersive gameplay, atmospheric effects, soft shadows, ambient occlusion, high-resolution textures, 3D models, accurate representation, military innovation, efficient layout, user engagement, seamless interaction, intuitive design, engaging mechanics.