Only one roleplaying game has a note on the cover declaring it "The book that was seized by the US Secret Service!" That RPG is GURPS Cyberpunk, a 1990 supplement for the Generic Universal Roleplaying System published by Steve Jackson Games.

On the morning of March 1st 1990, GURPS Cyberpunk author Loyd Blankenship and his wife were woken up by six Secret Service agents who raided their home, confiscating a computer, a printer and even their telephone. Then the Secret Service headed across Austin to the office of Steve Jackson Games, where Blankenship worked as a managing editor, to do the same. The office was not yet open for the day and the Secret Service agents almost broke the door down before Blankenship, still only half-dressed, explained that he had keys.

I emailed Steve Jackson to ask if he remembered the day his company was raided by agents whose normal job is to stand between the US president and bullets.

“Not terribly well!” he replied. “I did not come to the office during the raid. Our company president was there, called me to tell me it was happening, and said, 'Don’t come in - they are not letting anyone in the office.' So I did not meet the SS people on the day of the raid, though I got to spend more than enough time with them later."

The Secret Service agents tore open boxes, damaged a letter opener trying to pick a locked filing cabinet and, according to some accounts, ate jelly beans off someone's desk.

The Secret Service confiscated computers Steve Jackson Games used to run its BBS (which is what people used to have in the days before online forums and comment sections existed), as well as every computer with files relating to then-unpublished GURPS Cyberpunk. They tore open boxes, damaged a letter opener trying to pick a locked filing cabinet and, according to some accounts, ate jelly beans off someone's desk.

"They didn’t treat the office with respect," as Jackson puts it. "Things were generally a mess. Not vandalism - just dishevelment. I can’t confirm the jelly bean story - they weren’t mine. But they definitely bent a letter opener and left big scratches around the lock of a file cabinet."

At the time nobody knew why this was happening. The warrant granting permission for the raid was sealed - since GURPS Cyberpunk was taken, it was natural to assume that was the focus for some reason. Jackson describes the book as being heavily inspired by the high-tech low-life fiction of William Gibson and Bruce Sterling.

"Typical characters have 'cyborg' augmentations," he explains, "Though that’s not necessary. The most typical scenarios are espionage, high-tech heists, protecting from same, and combinations of the above with plenty of double-crossing. I should emphasise that even 30 years later, this is still fiction."

The core manual for GURPS Cyberpunk included rules for exploring cyberspace and hacking networks.

Jackson had a hard time communicating that to the Secret Service. In spite of the fact the rulebook contained rules for having your consciousness transferred to a gender-swapped clone, when he spoke to them the day after the raid he was told that his company was publishing "a handbook for computer crime". When he protested that it was clearly made up, he was repeatedly informed: "This is real."

The strangest thing about this story isn't that government employees couldn't tell the difference between a work of science fiction and reality, but that they'd only confiscated it opportunistically. Although the warrant was sealed at the time, leaving everyone to assume that GURPS Cyberpunk was the object of the raid, the truth is even odder.

It seems ridiculous now, but in the late 1980s hacker-mania swept the United States. The news breathlessly reported on computer crime and the movie WarGames had the public convinced kids were going to start a nuclear war.

"It was dumb, not to put a fine point on it," Jackson says, "and it was driven by the media, with the help of law enforcement (who liked playing up threats) and the 'hackers' themselves (who liked bragging, and inventing brags for the credulous, as much as any other smart teenaged boys)."

Jackson was told his company was publishing "a handbook for computer crime".

When a hacker calling himself Prophet broke into the mainframe of phone company Bell South in September 1988 and copied a file he found there, it was treated as serious business. It was only a text file, but it described the enhanced 911 system Bell South used to prioritise and identify emergency calls. The company valued this stolen file at $79,449 - an amount that was determined by adding together the wages of everyone who was involved in writing, editing and storing it, as well as the value of the computer hardware it was on ($31,000 for the computer, $6,000 for a printer and $850 for a monitor) and the Interleaf software it was made with ($2,500).

The information that document contained was not top secret. It was mostly administrative, and everything in it was available in a document sold to the public by Bellcore - Bell South's owner - for $13. By overvaluing this file and thus exaggerating the crime, Bell South attracted the attention of the Secret Service so they could use them to frighten off any kids who might think to breach their security again.

In his youth Blankenship had been a member of a hacking group called the Legion of Doom - the same group as Prophet - under the pseudonym "The Mentor". In 1986, after being arrested for computer crime, he wrote an essay called The Conscience of the Hacker, which became known as the Hacker Manifesto after it was published in a zine called Phrack. That same zine later published excerpts from the stolen Bell South document.

In the four years since his arrest, Blankenship had gone straight. He wasn't a teenage computer criminal any more; he had a real job. He still ran a BBS from home, though, and he worked for a company that owned one. One that Steve Jackson Games had jokingly dubbed "the Illuminati".

GURPS Cyberpunk drew heavily from works of '80s sci-fi such as Neuromancer, to the point where terms from William Gibson's seminal novel were highlighted with asterisks in the tabletop RPG's glossary.

The idea that a forum owned by an RPG publisher was worth being shut down by the Secret Service because they might republish a stolen text file full of publicly-available information is obviously laughable, and yet that's what happened. When the agents didn't find that file on the premises of Steve Jackson Games, they picked up a book about computers with Blankenship’s name on it and took that instead.

It took days for Jackson and his attorney to learn any of this, and months to get their hardware back. When it finally turned up, much of it was in an unusable state.

"It all arrived at the lawyer's office in one big box with no packing material," Jackson says. "For instance, a hard drive was just placed loose inside the cabinet of a PC, where it could bounce around on the motherboard during shipping. It's hard to put that down to simple ignorance; somebody was just being mean."

GURPS Cyberpunk's release was delayed, and it had to be rewritten almost from scratch based on playtest notes and memories. Losing the BBS, a direct line to their fans, was also a blow. "I recognise that it had its funny elements from the outside," says Jackson, "but the damage it did to the business forced me to lay off half my staff, which will never be funny."

Jackson brought the Secret Service, specifically the Chicago Computer Fraud and Abuse Task Force who had come to Austin for the raid, to court in a civil lawsuit. With help from a group of technologically-literate legal experts with an interest in the recent spate of computer crime cases - that same year 15 other raids occurred across the country as part of Operation Sundevil - Jackson and three of his employees won $300,000 in statutory damages and attorney's fees.

I recognise that it had its funny elements from the outside, but the damage it did to the business forced me to lay off half my staff, which will never be funny.

Those legal experts would go on to found the Electronic Frontier Foundation, a non-profit group dedicated to protecting civil liberties online. The raid also inspired science-fiction author Bruce Sterling, responsible for foundational cyberpunk novels like Schismatrix and Islands in the Net, to turn his hand to non-fiction, writing The Hacker Crackdown: Law and Disorder on the Electronic Frontier.

Steve Jackson Games survived, and still publishes games today, including Munchkin, Toon and the Discworld Roleplaying Game. Looking back on the raid, Jackson says it almost killed his company, "but not quite”.

“My best estimate, later, is that it cost us five years of growth,” he says.

Loyd Blankenship no longer works in the RPG business. These days he's on the other side of cyber security, working as a UX designer for anti-virus software maker McAfee.

GURPS Cyberpunk is still on sale. Its credits thank the United States Secret Service for "Unsolicited Comments".