zombies, Call of Duty: Black Ops II, perma-perks, glowing green effects, persistent upgrades, Juggernog, Quick Revive, Deadshot Daiquiri, Steel Barriers, Red Insta-Kill, Tombstone Soda, survival, game mechanics, eerie atmosphere, abandoned locations, post-apocalyptic, dark lighting, foggy environment, decaying structures, 3/4 view, action-packed scene, detailed textures, gritty aesthetic, dynamic shadows, immersive gameplay experience.