The game is essentially Risk but with Dark Eldar and Chaos Daemons. "It's like playing chess with toy soldiers and using a textbook for rules," says former Marine Samuel Corum, a combat photographer who served two tours of duty in Iraq.
Corum isn't exaggerating. The 40K Rulebook is 452 pages long. Each set of characters has a 100-page manual that explains its back story, abilities, and point values. The 40K wiki describes the Orks as being "dominated by the WAAAGH!, a gestalt psychic field they generate that affects the Ork psyche, which allows Orks to instinctively recognize who is 'bigga', and therefore who is in charge, since might makes right in Ork society."
In 40K, though, mythology is less important than victory. "My whole goal is to kill you," explains Charles Pope, a former Army sergeant. "I don't want prisoners." And when you're playing with another service member, that kill-or-be-killed attitude is A-OK. "It's a lot more fun to play games with servicemen because they have an ingrained sense of rules; they don't complain about them," says Neil Gilstrap, who co-hosts the 40K-centric podcast The 11th Company. They also enjoy flexing their strategic muscles. "How the mechanics of the game work, how to put together the best army, what units function the best," Carey says, ticking off military skills that translate to 40K. "[The game] satisfies the inner tactician in a lot of soldiers."
40K may not be a true simulation of armed conflict, but it's part of a centuries-long tradition of war games. After World War II, U.S. Navy Adm. Chester W. Nimitz credited gaming for helping the Allies prepare. "The war with Japan had been re-enacted in the game rooms here by so many people and in so many different ways," he said, "that nothing that happened during the war was a surprise — absolutely nothing except the kamikaze tactics towards the end of the war; we had not visualized those."