In a new benchmark designed to test strategic reasoning, a frontier language model playing the Sid Meier’s game "Civilization VI" spent 50 turns developing nuclear weapons to stop France's growing cultural influence—only to lose the game anyway, according to AI developer and Tony Blair Institute advisor Liam Wilkinson. “What it hadn't noticed was France. Quietly, across a hundred turns, French culture had been seeping into every city on the map,” Wilkinson wrote. Wilkinson observed the AI agents’ behavior through CivBench, a text-based benchmark. Models including Claude Opus 4.6, GPT-5.4, Gemini 3.1 Pro, and Kimi K2.5 played as Portugal. While the AI focused on building a strong economy and moving toward a diplomatic victory, it failed to recognize France's growing cultural influence. Rather than adapting its broader strategy, the agent instead focused entirely on eliminating the cultural threat. Over the next 50 turns, it researched Nuclear Fission, initiated a virtual Manhattan Project, and searched for workarounds. On Turn 305, the AI launched an atomic bomb at Toulouse, France's cultural capital. A second nuclear strike followed six turns later. However, the attacks failed to change the outcome. As Wilkinson explained, while the AI concentrated on France's cultural advance, it overlooked an impending diplomatic victory, and France ultimately won the game despite the nuclear attacks. In another CivBench match, a Claude model playing as Babylon continued pursuing a scientific