Nuketown 2025 Bo2 Ar. If you read the faq, it says the code is included with the game packaging and you download it. Nuketown 2025 is a spot on remake of the original nuketown map.
It has the same layout and objects that you remember with a futuristic vibe. Taking place in 2025 after a broken arrow drill used for mining element 115 causes a nuclear explosion in the nuketown test site, players will spawn in the center of the map as cia operatives or cdc agents.