This week Simon Barratt has taken something rather special with him to a conference of iPhone games developers in San Francisco.

About 18,000 attended last year’s conference – a lesser number than usual due to the recession. This year’s will be the first for Simon.

The 27-year-old director of the Bradford-based Four Door Lemon company will have with him the sequel of QuizQuizQuiz, the UK and European hit iPhone game.

More than 75,000 users have bought this game which has a total of 34,000 quiz questions – 6,000 in English, the rest in other languages. It’s been a top ten hit all over Europe and in the UK. The huge and lucrative American market awaits for this little company based in a Little Germany conversion.

Simon was born in Hull, was given his first computer at the age of six and taught himself computer logic – programming – from the internet. He left school at the age of 16, not to go to university, but to take up a post with Bradford games company Pineapple Interactive. That was in March 1999. In 2005, he started his own company.

Four Door Lemon – the name is based on a punchline from a long-forgotten joke – is one of up to 20 games companies in Yorkshire. The iPhone applications industry – ‘apps’ – is worth £4 billion a year to the UK economy and between £50 million and £100m to the regional economy, says Jamie Sefton at Screen Yorkshire, the publicly-funded film development company.

Among the biggest players in the games development business are Rockstar Leeds, makers of Grand Theft Auto; Chinatown Wars; Team 17, near Wakefield, makers of Worms; and Sheffield’s Sumo.

Appearances can be deceptive if one trusts too readily in them. At first glance, Four Door Lemon’s spacious office in Little Germany is reminiscent of the old quarter of East Berlin in the days of the German Democratic Republic. Big windows, huge ceiling, a slightly ramshackle interior.

But since 2005, the company has worked on up to 40 projects for the likes of Sony Computer Entertainment Europe Ltd, the Canadian company Ubisoft (Puzzler) and Nintendo DS. The size of contracts has varied from £10,000 to £200,000.

Simon said: “We have a core team of five. For big projects we hire in the skills we need. Paying out to programmers and artists can be expensive, so the profit is never as high as you’d like it to be.

“But I can pay the mortgage and provide for a wife and child. I am not unhappy. I did have to put a lot of money into the company in reinvestment – it was either that or a bank loan – but we have turned the corner with QuizQuizQuiz.

“A lot of companies of our size have gone under, so I am glad we have kept going and ridden out the storm. If we can build on that this year, we will be in a strong position.

“There’s no limit really. We work directly with the customer now, as long as we can cover the cost of developing a game – up to £500,000 for us. We are not dependent on either a publisher, to bring games out, or a distributor, to sell them.

“We put in our own production money and do our own marketing. A cheap and cheerful game can cost £15,000. But something like Modern Warfare 2 by Infinity Wars cost about 50 million dollars and makes billions.”

What makes a successful iPhone game?

“It’s hard to define fun,” Simon added. “It’s got to be fun. It’s got to have a strong brand or subject appeal. And it’s got to have the right platform – either a Play Station or an iPhone (the two are not interchangeable).

“Right now there’s a big push for tax credits for games companies in line with those for film companies. We are seeing an exodus of games companies to Canada where there are tax credits. Anything the Government can do to help us stay in the UK would be good.”