The cause was heart and kidney failure, his family said.

Mr. Calhamer (pronounced CAL-uh-mur) conceived Diplomacy at Harvard in the mid-1950s, and from the start its object was simple: to achieve world domination in as many hours (or days, or even years) as it takes.

Released commercially in 1959, Diplomacy has sold more than 300,000 copies. It was reported to have been a favorite game of Henry Kissinger; John F. Kennedy and Walter Cronkite were also said to enjoy it. In 1984 it was named to Games magazine's Hall of Fame, alongside stalwarts like Monopoly, Clue and Scrabble.

Over the years, Diplomacy — "Dip" to its most fervent adherents — has inspired a welter of fanzines, international tournaments and, most recently, online competitions.

Diplomacy plays out on a map of pre-World War I Europe, with each player — it is ideally suited to seven — representing one of the Great Powers of the age: England, France, Germany, Italy, Austria-Hungary, Russia and Turkey.

The game ends when a player wins by capturing 18 of the board's 34 strategic "supply centers," or when all players still standing agree that they are simply too bleary-eyed and cranky to continue.

Unlike many board games, Diplomacy leaves nothing to chance: there are no dice to roll (as in the comparable board game Risk, which relies on armies to conquer the world), no cards to shuffle (ditto), no pointers to spin. Instead it relies on strategy, cunning and above all verbal prowess.

In each of the game's compulsory negotiation periods, which involve whispering furtively in corners while simultaneously routing eavesdroppers, players in weaker positions band together against those in stronger ones.

What emerges from these sessions, which govern the moves on the board, is a world of quicksilver alliances: joint military campaigns are planned; deals are made, then abrogated, and new agreements arise to take their place. Foe is friend and friend is foe, and it is seldom possible to tell the two apart.

In short, Diplomacy rewards all manner of mendacity: spying, lying, bribery, rumor mongering, psychological manipulation, outright intimidation, betrayal, vengeance and backstabbing (the use of actual cutlery is discouraged).

It also rewards staying power. A typical game lasts at least six hours, and 16-hour games are far from unknown. In Diplomacy-by-mail, a version for far-flung players first popularized in the early 1960s, a single game can unspool over years.

Mr. Calhamer was an honored guest at many Diplomacy tournaments, at which he was by all accounts a good player but not a great one — he was apparently too kindly to succeed at his own game. The rest of the time he lived quietly in La Grange Park, a Chicago suburb, where he worked as a letter carrier while tinkering with other games, all unproduced.

Allan Brian Calhamer was born on Dec. 7, 1931, in Hinsdale, Ill., and reared in La Grange Park; his mother was a teacher and his father an engineer.

As a boy, exploring the attic of the family home, Allan encountered a book of old maps and was captivated. On its pages, the past really was a foreign country, with evocative names — Livonia, Courland, the Ottoman Empire — that conjured a distant era. From that book, Mr. Calhamer said long afterward, Diplomacy would spring.

At Harvard, from which he graduated cum laude in 1953, the young Mr. Calhamer studied European history with Sidney Bradshaw Fay. Reading Professor Fay's seminal 1928 book, "The Origins of the World War," about back-room intrigue among the Great Powers, he thought, as he later recalled, "What a board game that would make!"