The rule
One liar. One culprit.
Every case has five suspects and five statements. Exactly one suspect is guilty. The guilty suspect lies and every innocent suspect tells the truth.
No trivia or outside knowledge is required. Each generated case is validated at build time and must have exactly one solution.
The first 60 cases are initially open to search indexing; the rest remain playable but use noindex,follow while we measure quality and demand.