Targeted largely at conservative Christians, it's a violent video game with a difference: Combatants on one side pause for prayer, and their favored interjection is "Praise the Lord."

Critics say "Left Behind: Eternal Forces" glorifies religious violence against non-Christians. Some liberal groups have been urging a boycott, and on Tuesday they urged Wal-Mart (WMT) to withdraw the game from its shelves.

However, Troy Lyndon, CEO of Left Behind Games Inc., defended the game as "inspirational entertainment" and said its critics were exaggerating.

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He expressed greater concern about poor reviews from some video-game aficionados, saying the company would offer a free technical upgrade by Dec. 24.

Lyndon's company, based in Murrieta, Calif., has a license to develop games based on the popular "Left Behind" novels, a Bible-based end-of-the-world-saga that has sold more than 63 million copies.

Lyndon, in a telephone interview, said "Eternal Forces" has been distributed to more than 10,000 retail locations over the past four weeks. He said sales were going well, but declined to give specifics.

The real-time strategy game has received a T (for teen) rating, as its makers had hoped. It offers more violence than an E-rated children's game, but less graphically than M (for mature) rated games that have often been criticized by conservative Christian groups.

"Our game includes violence, but excludes blood, decapitation, killing of police officers," the company says on its Web site, noting that a player can lose points for "unnecessary killing" and regain them through prayer.

The game's story line game begins after the rapture, when most Christians are transported to heaven. Earth's remaining population is faced with a choice of joining or combatting the Antichrist, as embodied by a force called the Global Community Peacekeepers that seeks to impose one-world government.

The game's critics depict the ensuing struggle, set in New York City, as one fostering religious intolerance.

"Part of the object is to kill or convert the opposing forces," said the Rev. Tim Simpson of Jacksonville, Fla., who heads the Christian Alliance for Progress. "It is antithetical to the Gospel of Jesus Christ."

Simpson, whose group was formed last year to counter the influence of the religious right, joined in a news conference Tuesday at which he and other speakers urged Wal-Mart to discontinue sales of "Eternal Forces".

Wal-Mart indicated it would continue selling the game online and in selected stores where it felt there was demand.

"The product has been selling in those stores," said spokeswoman Tara Raddohl. "The decision on what merchandise we offer in our stores is based on what we think our customers want the opportunity to buy."

The game's makers contend that the violence from the good side — the Tribulation Force — is exclusively defensive, and should not be seen as contrary to church teachings.

"Christians are quite clearly taught to turn the other cheek and to love their enemies," the company Web site says. "It is equally true that no one should forfeit their lives to an aggressor who is bent on inflicting death."

Lyndon said he and his fellow executives hoped to ease critics' concerns.

"They're good-minded people," he said. "They want to keep us from making games that are jihad in the name of God."

Simpson, a Presbyterian Church USA pastor, said he was dismayed by the concept in "Eternal Forces" of using prayer to restore a player's "spirit points" after killing the enemy.

"The idea that you could pray, and the deleterious effects of one's foul deeds would simply be wiped away, is a horrible thing to be teaching Christian young people here at Christmas time," Simpson said.

Anther participant in the critics' news conference, author Frederick Clarkson, argued that "Eternal Forces" — though less violent than many other video games — was more troubling in some ways.

"It becomes a tool of religious instruction," he said. "The message is. ... there will be religious warfare, and you will target your fellow Americans, people from other faiths, people who you consider to be sinners."

Clarkson faulted Focus on the Family, a Colorado-based Christian ministry often critical of violent video games, for publishing a positive review of "Eternal Forces" on one of its Web sites.

"Eternal Forces is the kind of game that Mom and Dad can actually play with Junior and use to raise some interesting questions along the way," wrote the reviewer, Bob Hoose.

Other online reviewers — writing for hardcore gamers — have been less impressed.

"Don't mock 'Left Behind: Eternal Forces' because it's a Christian game. Mock it because it's a very bad game," wrote GameSpot reviewer Brett Todd.