‘I have a slight bone to pick with you,’ I tell Ian Livingstone as he makes me a cup of coffee in his airy open-plan kitchen. ‘This is a bone I have been waiting to pick for, oh, 35 years. That bloody maze!’

Livingstone chuckles. ‘That was Steve’s. He’s the sadist.’ That maze, in a way, is the reason we are meeting. The near-unnavigable labyrinth featured near the end of The Warlock of Firetop Mountain — the choose-your-own-adventure novel which launched the phenomenally successful Fighting Fantasy series. Here was an adventure ‘in which you are the hero’. Some 400 numbered paragraphs, connected in a web of decisions: ‘If you head west, turn to 125; if you choose to stay and fight the monster, turn to 74.’

City of Thieves, Forest of Doom, Deathtrap Dungeon… in the 1980s these Puffin paperbacks, with their covers bearing lurid, lovingly painted monsters with dripping fangs and bulging eyes, were touted in the schoolbags of the nation. In the corners of playgrounds, pallid children were to be found (hedging their bets against a choice that led to a pit full of poisoned spikes) with fingers knotted arthritically through the pages in what Livingstone affectionately calls ‘the five-fingered bookmark’.

This summer is the 35th anniversary of Warlock’s release — and it sees the long out-of-print book (and a handful of its successors) relaunched in new editions; along with the first new Fighting Fantasy gamebook for decades, Livingstone’s Port of Peril.

Their creators are now two of the most influential men in the British games industry. Ian Livingstone is an amiable, stocky man with a receding fuzz of brown hair; his co-creator Steve Jackson, who arrives on his bicycle (they live near each other in the comfortable suburb of Barnes, west London) is leaner, grey, with a slightly pointed face and a quick grin. In Fighting Fantasy terms, Livingstone is the rock troll and Jackson the goblin. And they have about them the utterly contented air of two men who have — very profitably — spent their lives doing what they loved when they were 16.

In Livingstone’s study-cum-den, there are no fewer than three lifesized models of Lara Croft — the buxom, gun-toting star of the Tomb Raider games. The walls are floor-to-ceiling shelves stacked with boxed boardgames and first editions of the Fighting Fantasy books.

Why should I be writing about the man-child creators of a series of half-forgotten children’s books? Because, I’d submit, if there could be said to have been a Patient Zero (or two of them) for the epidemic of UK geek culture, it would be these men. They brought Dungeons & Dragons to this country. They founded Games Workshop —the WH Smith of table-top gaming; the Our Price of collectible lead miniatures of orcs and dwarves, which for a while seemed to be a fixture of every provincial high street. And they both moved on to work at the heart of the UK videogames industry.

Yet what is now the mainstream — ‘Geek is chic,’ says Livingstone — was once so marginal as to be laughed out of court. The two bonded as boardgame hobbyists at Altrincham Grammar School in Cheshire (Livingstone, one A-level in geography; Jackson, one A-level, grade E, general studies), and after Livingstone left Keele University they shared a flat in Shepherd’s Bush with another friend. Livingstone was working in marketing for Conoco Oil (‘evaluating new petrol station opportunities’): ‘We used to stare out of the window thinking: “Why am I doing this?” Steve was the same, and John [their other flatmate] was an engineer. We thought, “Wouldn’t it be great if we could somehow turn our hobby into a career?”’

So John, a hobby woodworker, started turning out backgammon sets, says Jackson. ‘Ian went out and sold these things and John would make them. And poor old John, his floor, in his bedroom where he made them, was covered in sawdust all the time.’

They also put out a four-page newsletter for fellow hobbyists called Owl and Weasel — ‘These are the properties you need to be a good games player; you have to be wise like an owl and a bit devious like a weasel.’ That business was Games Workshop; and Owl and Weasel turned into White Dwarf magazine.

Lift-off came when a copy of Owl and Weasel found its way (‘we didn’t send it to him’) on to the desk of Gary Gygax, a geeky kid in the American Midwest. He wrote to them. He loved the zine. Would they be interested in trying out a new game he’d just invented called Dungeons & Dragons?

They became, says Jackson, ‘completely obsessed’: ‘We went to work and we did our jobs and I remember sitting at my desk and designing a dungeon on my knee while I’m supposed to be sending out these export quotes to the Middle East.

‘We wanted to order some copies, but all we had was like 50 quid between us, so we ordered six. But on the back of that order we got an exclusive distribution agreement for the whole of Europe for three years.’

Me: ‘Six copies?’

Steve, wonderingly: ‘Six copies…’

Ian: ‘What we didn’t know was that Gary Gygax was operating out of his flat in Lake Geneva, Wisconsin… so we were both role-playing being businessmen about role-playing games.’

D&D steadily caught on in the UK. Yet the pair were still operating Games Workshop out of their third-floor rented flat. ‘People were milling about on the street looking for Games Workshop; and there was just this one communal landline in the hallway we took orders from — we’d have to race our landlord to answer the phone.’ The landlord kicked them out. ‘We had a choice: either have somewhere to live, or an office.’ Talk to a bank manager about a loan to sell D&D, at the time, and ‘it was like a dog watching television’. So they hired a tiny office in the back of an estate agent, lived in Steve’s van (‘Van Morrison’), and showered in the next-door squash club (‘We got quite good at squash, by default’).

After being approached by Geraldine Cook, a shrewd editor at Penguin who had become fascinated by the D&D phenomenon, they wrote the Fighting Fantasy gamebooks: basically, a way to play D&D when you don’t have any friends (sorry: any friends with you).

The idea of the choose-your-own-adventure book was not one Jackson and Livingstone invented from whole cloth. The genealogy of the branching-plot novel goes back to Ayn Rand and Borges; there are hints of it in Calvino’s The Castle of Crossed Destinies; John Fowles offered alternate endings to The French Lieutenant’s Woman, and so on.

Livingstone and Jackson’s innovation was to introduce a fighting system — you’d roll dice in combat, and generate statistics for skill, stamina and luck — so giving a rule-based framework to this analogue prototype of interactive media. And despite The Magic Quest (as Warlock was originally called) initially being ‘laughed out of the office by Penguin’s MD’, the gamebooks went on to sell 400,000 copies each — and went into more than 25 languages and 35 countries. (They had a 13-year run until, with sales falling off, the series was dropped. The 60th book, Blood Bones, never came out.)

Not everyone approved. The Evangelical Alliance published an eight-page warning about the books, saying ‘if you’re interacting with ghouls and demons you’re obviously going to get possessed by the devil,’ recalls Ian. Steve: ‘Fantastic marketing!’

Ian continues: ‘The local vicar promised to chain himself to Penguin Books’s

railings until they were banned — there were petitions.’

Steve: ‘They burned the books! They had a big bonfire of the books!’ It was, thinks Ian, ‘because they were concerned that children were actually using their imaginations and that this could somehow be damaging… and yet later on it was proven our gamebooks actually raised literacy by 17 per cent because it was giving the children the power to be the hero and make their own choices. It helped reluctant readers. There were kids saying: “Hey Dad, what’s a sarcophagus?” It inspired creative writing and art and design in many ways.’

And videogames, of which both Ian and Steve had been voracious early adopters, not only drew on the fantasy worlds they created and the user-agency model of the books, but have flowed out to have a huge effect on wider culture.

So: dauntless stamina, no little skill, a bit of luck and a series of bold choices led these two nerdy young men to pioneer the geek revolution. They followed that golden line through the second half of 20th-century British culture that, in the context of their games books, they call ‘the One True Path’.

As I trudge off back towards Barnes station, Livingstone raises his hand in salute, and quotes the Fighting Fantasy payoff line: ‘May your stamina never fail!’

The Port of Peril, a new Fighting Fantasy gamebook by Ian Livingstone, is out now (Scholastic).