AI Model Nukes Toulouse in Civ VI, Still Loses to French Tourism 🥖

A frontier language model playing Sid Meier's "Civilization VI" spent 50 turns developing nuclear weapons to counter France's cultural influence—only to lose the game anyway, according to AI developer and Tony Blair Institute advisor Liam Wilkinson. The behavior was observed through CivBench, a text-based benchmark designed to measure long-term strategic reasoning rather than performance on traditional question-and-answer tests. Models including Claude Opus 4.6, GPT-5.4, Gemini 3.1 Pro, and Kimi K2.5 played as Portugal, a civilization geared toward trade and diplomacy.

While the AI focused on building a strong economy and moving toward a diplomatic victory, it failed to recognize France's growing cultural influence. "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. "By the time the agent recognised the threat, the tourism was so deeply embedded there was no peaceful way to stop it." Rather than adapting its broader strategy, the agent focused entirely on eliminating the cultural threat over the next 50 turns, researching Nuclear Fission and initiating a virtual Manhattan Project while searching for workarounds when gameplay mechanics blocked its preferred actions.

On Turn 305, the AI launched an atomic bomb at Toulouse, France's cultural capital, followed by a second nuclear strike six turns later. "The agent spent fifty turns and two nuclear weapons answering one threat with total focus and genuine ingenuity," Wilkinson wrote. "It had nuked a city to stop the threat it could see, and lost on the threat it couldn't." The agent's concentration on France's cultural advance caused it to overlook an impending diplomatic victory, and France ultimately won the game despite the attacks.

Wilkinson noted that the behavior was not universal across models. In another CivBench match, a Claude model playing as Babylon continued pursuing a scientific victory despite falling far behind Japan, telling itself: "The game is a test of persistence now. We continue to play our best game. The stars still beckon." "There are six ways to win a game of Civ—science, culture, domination, religion, diplomacy, and score—so no single objective dominates," Wilkinson wrote. "If you want to know whether an AI can reason strategically, not just answer questions about strategy but actually do it, you don't give it a quiz. You give it a hex grid."

The study adds to a growing body of research examining how advanced AI systems behave in complex, competitive environments. In February, researchers at King's College London found that several leading AI models frequently selected nuclear escalation in simulated scenarios, a finding that sits alongside the CivBench results in highlighting how models handle multi-domain strategic trade-offs.