At Computer Gaming World magazine, where people play games for a living, playing Doom during working hours is forbidden. "It just keeps them there too long," says editor in chief Johnny Wilson.
People have been known to play non-stop up to 36 hours, says Ian Mapleson, a student at Heriot Watt University in Edinburgh, Scotland, who is writing a thesis on the game.
"I must confess, myself and three friends did play a co-op Doom session that lasted 28 hours," he says. "How's that for obsession?"
Doom is an unabashedly violent action game with a boilerplate plot pitting you against aliens on a godforsaken moon of Mars. You defend yourself with an arsenal that includes a pistol, pump-action shotgun, rocket launcher and chain saw. Blood flows liberally. "It has a visceral quality that's very much in your face," Wilson says.
But Doom's attraction is more than blood lust. Its 3-D graphics have left players - and the industry - agog.
Other games have 3-D graphics, which allow players to move forward or backward or spin in any direction and see a continuous image as if they were there. But Doom's 3-D environment seems seamless. And it's very fast - a key feature in an action game and a difficult technical trick to accomplish.
Innovative use of lighting and stereo sound only add to the realism. Players have complained of motion sickness and vertigo.
"Doom is visually, emotionally, perceptually and mentally the most gripping computer game made to date," says Mapleson.
While major software companies concentrate on CD-ROM games with live actors and lots of video, Doom relies on none of that. Perhaps that's because Doom's creator, Id Software, is not anyone's vision of a major software company. It consists of 10 people working out of a suburban Dallas office. What's more, Id gives away part of the game.
The first chapter of Doom, with nine levels of play, is available as "shareware" - it can be downloaded via computer for free from numerous electronic bulletin boards. Or it can be shipped, for a handling charge, from shareware outlets or from Id (800-434-2637).
An expanded version of the game - with two additional chapters and more weapons, creatures and features - can be bought only from Id. It costs $40 (Doom can only be played on IBM-compatible computers).
"We have faith in the game itself, so we give away a portion of it," says Id's Jay Wilbur. "It has become a beacon for us."
Wilbur estimates there are more than 1.5 million copies of the first Doom chapter in circulation. Id has sold about 70,000 copies of the expanded version and expects sales of 200,000 by year's end. There are discussions about a movie based on the game.
Some computer games from powerhouse software companies, such as LucasArts' Rebel Assault, have sold more than 400,000 copies. But Id spends a comparative pittance on marketing, distribution and packaging.
"You upload it to a major bulletin board, and if it's a really good program, it'll be distributed really quick," says Jeff Frownfelter of shareware distributor Public Brands Software of Indianapolis. "It only took a week (for Doom) to be on most major bulletin boards and a lot of smaller ones."
Id had another hit in 1992 with Wolfenstein 3-D, similar to Doom, except the 3-D graphics weren't as advanced and the enemies were Nazis, not aliens. It sold 150,000 copies (not including shareware giveaways). A retail version, Wolfenstein 3-D: Spear of Destiny, has sold 135,000.
With Wolfenstein, Id discovered computer hackers would create customized versions of the game that they would share with other players. When Doom came out in December, Id encouraged these hackers, releasing key programming information.
This has created a cottage industry and further fanned the game's popularity. Hackers have created new levels of the game and modifications that turn Doom's demons into replicas of Barney the dinosaur or add sound effects from The Simpsons, Monty Python or soul singer James Brown.
"We're all quite flattered over it," says Wilbur. "For the most part, we're very giving on this issue. It gives legs to the game."
These add-ons are exchanged on bulletin boards, online systems and the Internet. These sites also are clearinghouses for players searching for opponents. ( Doom can be played by multiple players via modem, a local network or the Internet.)
Later this year, a retail version, Doom II: Hell on Earth, with new levels and some new features, arrives in stores. Id also is working on a cartridge version of the original Doom for Atari's new Jaguar game system.
The follow-up to Doom, due next year, is a game called Quake. It promises to offer what Wilbur calls "six degrees of freedom" - 3-D effects that allow players to look up and down as well as side to side.
Curiously, Doom's lavish violence has aroused little criticism, perhaps because it's not sold in stores or widely advertised. In any case, Id is unapologetic.
"We're not going to sell out," says Wilbur. "The game is violent, it's bloody and it will not be changed for any reason."
There are shareware versions of everything from word-processing programs and spreadsheets to games and DOS, Windows or Macintosh utilities.
Shareware typically is created by entrepreneurs, who post their work on bulletin boards, hoping people will like it enough to pay for it on the honor system.
Typically, you'll pay $3 to $5 for a shareware program on diskette, which gives you the right to try it for 30 days. If you like it, you are expected to register your copy and pay a fee that is usually less than a comparable commercial software program. Sometimes, you'll receive additional features as incentive for registering your shareware.
Although they don't have huge development budgets like the big guys, shareware authors often are on the cutting edge. Some well-known retail software, such as Kid Pix and the communications program Procomm, began as shareware.