On a gloriously comfortable summer night in Dupont Circle, three pairs of men sat hunched over concrete tables, intently studying the small plastic chess pieces arrayed in front of them.

Nearby, a group of friends, several of them clutching beers, loudly debated the relative merits of various boxers. One of them, Billy Cooper, launched into a story about the time he was tricked into a cage with a gorilla ("I thought it was a monkey!") he'd been paid $100 to fight. His companions guffawed.

But none of the chess players raised an eyebrow. Too absorbed in their own universe of kings, queens, knights and pawns to be moved by tall tales, they weighed their next moves and raced against the game clocks ticking away at their sides.

So it goes on summer nights in Dupont Circle, where dozens of area chess players take advantage of balmy weather to play their favorite game deep into the night and the early morning.

Regulars say there are about 30 players who frequent the park at night. They range in profession from blue-collar to executive; the common thread that connects them is chess fever, a condition they describe as ongoing and unstoppable.

Part of the draw is the promise of competition, since on any given night players of varying levels -- from beginners to masters, those who play in serious tournaments -- are likely to be looking for a game.

"Chess is like a drug. Once you're addicted to it, you can't get off it," said William Burts, 29, who plays at the circle often.

Many of the regulars say they learned to play on the 10 concrete tables in the park, where the unwritten rules allow beginners to take on more advanced players. The better players often give handicaps to their less experienced opponents.

Most of the regulars play speed chess, in which timers are used. Evenly matched players usually get five minutes apiece to complete all their moves in a game; better players can handicap themselves by allowing five minutes to their opponent and only one or two minutes to themselves.

Though the less-experienced players usually take their lumps in such match-ups, they also pick up tips on strategy and tactics.

"When I first stepped into this city, I couldn't play a lick," said Charles Bullock, a postal worker who has been playing in the park for several years. "Now I'm getting pretty good."

"If you're trying to learn, you can play a master and learn a trick or two," agreed Anthony Cole, a student at the University of the District of Columbia and another circle regular.

The circle is also a magnet for players who are just passing through town and in the mood for a game.

One recent Saturday, Maurice Turner, a 24-year-old master from New York, spent nearly five hours at one of the tables. Turner said he was in town to visit a friend, who is also a chess player. "I asked him where the action was," he said.

By the end of his visit, Turner had played about 40 games. He won all but two, he said.

Even though car traffic buzzes almost continuously and an occassional siren pierces the night, Bullock said there are fewer distractions playing at Dupont Circle than at home. "If you play at home, nine times out of 10 your wife wants you to come to bed or the phone rings," he said.

Most of the players compete for fun, but there are chessboard versions of pool sharks. One good player who sometimes competes for money -- and who requested anonymity, since gambling on U.S. Park Police territory isn't exactly legal -- said he can win up to $100 a night.

But most said they play for enjoyment. "I'm a purist," explained Charles Roberts, 35, a computer programmer. "I'll play for money if someone wants to, but mostly I play for the love of the game."