Of the millions of gamblers who have rushed to play Texas Hold 'Em and other fast-growing poker games online, Roger Gabriel isn't the most intimidating.

The 30-year-old engineer from Newport Beach, Calif., started playing for money only a month ago. He lurks online at the chicken-hearted tables where the biggest ante is 4 cents. Even there, he can't win consistently.

But Gabriel has a potentially powerful alter ego. In his spare time, he is perfecting a computer program to go online and play the game for him. His "BlackShark" software is a work in progress. But Gabriel has no doubt that such programs eventually will be championship quality.

"In the future," he said, "robots are going to take over."

Gabriel is one of an increasing number of computer professionals who design poker robots, or "bots," that pose as human gamblers but can play endlessly without tiring or losing concentration — for real money.

Although not yet good enough to beat skilled humans consistently, these programs are seen as a threat by online casinos and the gamblers who spend billions of dollars chasing big pots.

"There are already lots of robots playing online, and that's definitely unethical. They should identify themselves," said Paul Magriel, a veteran professional poker player.

The march of the machines will be celebrated July 12-15 in Las Vegas with the world's first money tournament for robots, and the $100,000 prize is drawing a handful of coders out of anonymity.

The emerging technology does more than raise the stakes for real people and online casinos. It also raises fundamental questions about how far computers have come in mimicking and improving on human behavior.

Computer programs have conquered checkers, chess and backgammon. By rapidly evaluating plays more moves ahead than a person can, computers routinely beat strong human players.

Backgammon programs, which had to adapt to the random element of dice, grew so good by the late 1990s that they changed strategic wisdom built up over 2,000 years, influencing how the best humans play the game.

But in poker, psychology matters as much as probability.

This makes poker-bot design fascinating to academics such as Jonathan Schaeffer, a computing science professor at the University of Alberta in Edmonton who for 14 years has headed a project to build poker programs.

Schaeffer said cards are more likely than chess to produce computing approaches useful in the real world, because poker players must deal with incomplete information. But before such research can contribute dramatically to solving global dilemmas, Schaeffer said, it has to solve the challenge of poker — and that's several years away.

Robot designers Ken Mages of Evanston, Ill., is further along than Gabriel. But while their electronic progeny might win at small-stakes tables, they usually fall apart when the human competition is stiffer.

After two weeks of programming, Mages said, "I could sit down at a 50-cent table, put 50 bucks in the account, go to bed and wake up with at least $75." The most Mages said he won that way was $250; he never lost.

Mages struck a deal with Los Angeles public-relations executive Darren Shuster to set up the Las Vegas contest, dubbed the World Series of Poker Robots. They persuaded Antigua-based GoldenPalace.com to put up the prize money.

Even though GoldenPalace bans robots, the publicity-craving virtual casino was a natural target, having spent $28,000 last fall for the cheese sandwich said to bear the image of the Virgin Mary.

Organizers have other headline-grabbing gambits in mind: They plan to invite the winner of the human World Series to go up against the winner of their robot contest, although no one expects the computer code to triumph — at least, not this year.

Computer-gaming experts said the robots have some major hurdles to overcome before they have a chance against the world's top human beings — especially in multi-player games with no betting limit.

Bluffing can be programmed: For every 100 worthless hands, for instance, a machine might be instructed to bet heavily five times. A bigger issue is the need for abstract-pattern recognition.

The need to recognize patterns comes when anyone new sits down at the table. Computers can store and process millions of past hands, but they have too little data on each new competitor.

Magriel thinks a better-than-human poker program is inevitable in two or three decades.

"It was a little depressing in chess and backgammon that computers got so good," Magriel said. "In poker, it won't really depress me. I sort of expect it at some point."