Sergei's head, zombie, Firebase Z map, Call of Duty, decapitated, military base, tropical vegetation, abandoned structures, overgrown, dark atmosphere, eerie, scattered equipment, dim lighting, moonlit night, searchlight effects, foggy, detailed textures, rusted metal, concrete bunkers, high contrast shadows, 3/4 view, dynamic angle, action pose, horror theme, detailed environment, immersive, game art style.