Question: How is it possible for a football team to score two goals while conceding only one, yet lose the game and be quite happy?

Answer: They are playing Fútbol Callajero - Street Football.

Pablo Hewstone Arqueros, the project manager of CHIGOL, in Santiago, Chile, explains how, in his unique brand of football, the winners can be losers, and the losers winners - yet both sides end up victorious.

"The team that gets more goals is awarded three points, with one point for the losers. If there's a draw they get two points each. But before the game starts, they decide on the rules. There is an agreement about playing for certain sporting values: respect, clean play, fairness to female players and solidarity."

This is the crucial difference. These values also score points, just as much as goals. And the assessment of these virtues, and the points awarded thereby, is made by the teams themselves. At the end of the game the two sides have a discussion, through the mediator, to see which team has best complied with the rules; and once the scores have been totalled, along with the actual goals, they decide on the winner.

"The team who has scored few goal can win the game!"

"And that"s why a team who has scored fewer goals can win a game!'

Pablo smiles, inviting us to agree that all this makes complete good sense. It's kind of difficult to imagine this working in the English Premiership, say. With Manchester United and Chelsea getting together after the final whistle, to decide who's done the least swearing.

But this is not Old Trafford or Stamford Bridge. This is Cerro Navia, a run-down suburb in the Chilean capital, known for its huge disparities in wealth. In this squalid area where the police are noticeable by their absence, crack dealers are not far away and graffiti celebrating Che Guevara is everywhere.

But that's why CHIGOL works here and not elsewhere. It's maybe in places like this, where young men have little to do other than scrap, steal, smoke chuca and drink, where the bizarre rules of Street Football make complete sense.

Pablo warms to this very theme: "Winning or losing the game isn't the most important thing. The most important thing is the relationship that's created among the young people, the joy of the game, and that they evaluate themselves in order to get the points."

The abiding mystery is how, amid a culture of macho violence, the players can be persuaded to conform to these lofty ideals. We soon see it comes down to leadership - Pablo's most of all. He has a mixture of sternness and kindness. With his rugged, stubbly features, and his piercing blue eyes, he bears a resemblance to a young Charlton Heston. And maybe he also has the heroism of an old-style Hollywood hero in a tough environment like this, with a basic support staff of only two, he faces greater odds than any matinee idol in a swashbuckling epic, fighting his way out of the castle dungeon.

CHIGOL began in 2005, as part of the streetfootballworld network, which is supported by FIFA's Football for Hope movement. Pablo heard about Street Football's work in Argentina. He made contact, and was invited to Buenos Aires to see how it worked.

The aim of CHIGOL is the social transformation of a neighbourhood and, more crucially, of individual lives. When Pablo returned to sunny Santiago, filled with street football dreams, the first thing he did was to gather interested people, and clear a public space - a domain where youngsters could come together in a peaceful way around a soccer ball.

Might have ended up as gang leaders

He believes that, for many young people, the project arrived just in time. There are workshops and weekly training sessions for those with leadership potential, and some of these candidates might have ended up real gang leaders - given another few months.

CHIGOL works with and in as many schools as its limited resources allow. There are offshoots in other areas of Santiago and in Valparaiso and Puntas Arenas. The aim is to spread the project throughout Chile, to start a national league and to hold international competitions in one of Santiago's main boulevards.

Pablo's two helpers are Juan and Jorge. Both were mired in hopelessness before CHIGOL happened along. Half-alienated from their families, they haunted the drug-ridden alleys.

"I was involved," Jorge admits, "in the kind of world where I thought I'd either be a delinquent for the rest of my life, or I'd end up in prison, or dead. I nearly died once from a vicious stab wound. My prospects weren't very good!" He hung out with Juan, ‘el pelaito', ‘the skinhead', and they were always boozing, drugging and brawling. Now they are comrades in CHIGOL, trying to help friends and neighbours out of the rut.

When Jorge feels listless and pessimistic, Pablo is there to motivate him: "With his way of being half-crazy, euphoric, it's contagious." Jorge is also studying computer technology at university, so he will be able to help his community with the internet. CHIGOL has assisted his mother in setting up a small sewing business, where she hopes to employ teenage single mothers. Now she is happier - not least because her son feels closer. When we meet her in her humble house, with its female dummies and sewing machines, she tells us Jorge has been "born again".

He was even trusted with a bicycle

Juan, the community co-ordinator, followed a similar path. His serious face seems to reveal his troubled past. He tells us that between thirteen and sixteen he hung around on corners and got high. Then someone invited him to a Street Football game. He didn't want to go, but was somehow persuaded. He was allowed to play even though he was drugged - and he was even trusted with a bicycle so he could go home to get changed.

That trust meant a lot to him, along with a stern but kind after-match chat with the teacher; he sensed, at once, that this discipline was a way forward; soon after that, he began to feel he could help others, as he had once been helped.

He has now given up drugs and booze: "I tell people Street Football is my drug now, this is what fulfils me. I could spend my whole day playing street football. Playing and teaching. The truth is that I know a lot about it. I go and speak to twenty people, and out of those there may be five who are off the rails, and I talk to them and tell them my story. I can identify with them, and that's what really fulfils me."

It's a simple story, and a heartening one. How does it work? Maybe it's no mystery. With CHIGOL's unique brand of street football you don't need money, needles, or guns to make yourself happy; you don't need cars or cocaine or stolen bling

In fact, you don't even need goalposts. All you need is some friends, and a ball, and a patch of ground. And someone to count the swearwords.