Which AI Lies Best? LLMs play a 1950s betrayal game by John Nash

The Perfect AI Stress Test

So Long Sucker was designed in 1950 by four game theorists including John Nash (of "A Beautiful Mind" fame). The game has one brutal property: betrayal is mathematically required to win.

This makes it ideal for evaluating AI capabilities that standard benchmarks miss:

Strategic Deception — Can the AI lie convincingly ?

— Can the AI lie convincingly ? Trust Modeling — Does it know when to trust and when to betray?

— Does it know when to trust and when to betray? Multi-agent Negotiation — How does it handle alliances?

— How does it handle alliances? Long-term Planning — Can it set up betrayals turns in advance?