Poker is a family of games that exhibit imperfect information, where players do not have full knowledge of past events. Whereas many perfect-information games have been solved (e.g., Connect Four and checkers), no nontrivial imperfect-information game played competitively by humans has previously been solved.
There is some evidence that professional poker players tend to have higher than average IQs, though poker skill involves multiple factors beyond raw intelligence: A study of young poker players found their mean IQ was 112, compared to a norm mean of 100. Players identified as "experts" had a mean IQ around 120.