A MIDDLE-AGED man recently sat in his high-rise apartment in Manhattan and commanded ancient Grecian fields to bring forth hunters, miners, builders and soldiers. Soon there were fortresses and armies to storm them. A short time later came the inevitable carnage -- flaming ramparts and rotting bodies -- that wars have wrought through the ages.

This warfare was strictly play, all part of a popular computer strategy game called Age of Empires. The player, a small-business owner, was battling not only to win the game but to win a contest within himself. He is obsessed, he said, with playing war strategy games on his computer.

''There is a compulsion to play the game over and over until you win,'' said the man, who spoke on the condition that his name not be used to protect his reputation with clients who would not understand his fixation.

He has taken part in death matches that have started around 10 P.M. and lasted until 3 the next morning. ''That's without getting up to get a glass of water, anything to eat or going to the bathroom,'' he said. ''The game totally absorbs you.''

Many experts on obsessive behavior agree that there are striking similarities between addictions to substances like drugs and food and addictions to activities like gambling, shopping, sex and computer games. Some addiction counselors have begun to focus on compulsive game players.

But help, addiction experts say, seldom means giving up the games or computers. A common approach to treating computer game addicts is to try to teach them moderation, said Peggy Reynolds, a professor of human development counseling at Vanderbilt University in Nashville.

''You can't go cold turkey,'' said Dr. Reynolds, explaining that asking a compulsive game player to quit would be like asking an overeater to stop eating. ''Computers have become part of our life style. People have to know how to manage them.''

''It is addictive,'' said Monty Smith, a 23-year-old Brooklyn chef who calls himself an obsessive home computer game player. ''It can be like a drug.''

The business owner said it did not matter whether the games, which usually cost about $50, were set in early southern Europe or on mechanized fantasy planets whirling deep in space. What matters is that they be intellectually engaging.

''I have the need to win,'' the man said. ''I feel like I have to overcome the forces that the computer is throwing against me.''

A 35-year-old woman, who asked not to be identified to protect her husband's identity, said she had become alarmed by her husband's nightly marathon playing of computer shoot'em-ups like Doom and Quake. She called the games ''electronic crack.''

Maressa Hecht Orzack, founder and coordinator of computer addiction services at McLean Hospital in Belmont, Mass., one of the few programs that specifically treats computer game addiction, said she had recently spoken with a drug user who plays computer games. ''He said the games gave him the same kind of feeling he got when he was on amphetamines,'' she said.

Many of these players may be in denial, she added. ''The wives of these men, their companions, are the ones who often finger this,'' Dr. Orzack said.

In the early 1980's, teen-agers and young adults troubled their parents by obsessively playing coin-operated computer games in arcades. Dr. Orzack said that today, many of her patients who considered themselves home computer game addicts were in their 40's, 50's or older. Almost all are men.

Because computer game addiction is relatively new, there are no reliable statistics on the depth of the problem, Dr. Orzack said. She often learns of a game addiction, she said, after it has caused problems with someone's job or marriage.

That is not surprising, said Dr. William S. Pollack, a psychiatrist who is the director of the Center for Men at McLean Hospital, which is affiliated with Harvard Medical School. He said addicts were often dodging things like job worries and marital disputes.

''What lies behind the fascination with the games is ancient,'' he said. ''The games are a new symptomatic way of expressing an old problem: midlife dissatisfaction.''

''For some, their dreams of what life would be like when they were 45 or 55 were not coming true,'' Dr. Pollack said. ''They are looking for alternatives, something to take away the pain.''

Playing a sophisticated computer game, especially in a darkened den, is an isolating behavior, said Dr. Reynolds, of Vanderbilt. She said men were especially vulnerable to isolating experiences like playing computer games because they were generally less comfortable than women in social settings.

''Playing computer games can be a way of isolating from the stress of being in a relationship, either with the people in the home or in a given community,'' Dr. Reynolds said.

The middle-aged game player who asked not to be identified said that after years of excessive use of computer games, he had begun preferring to stay at home alone with his games rather than venturing out. ''It was easier to stay in with the game than to go out and look for a girlfriend,'' he said.