Media playback is unsupported on your device Media caption How two Polish men created a blockbuster global gaming phenomenon

When Barack Obama visited Poland in 2011, the country's Prime Minister Donald Tusk chose to give the US president a copy of the computer game The Witcher 2 as a present.

For Mr Tusk the gift represented modern Poland.

When President Obama returned to Poland last month he spoke favourably about the game.

Sitting in his modern glass and brick Warsaw office, Marcin Iwinski, the co-founder and joint chief executive of the company between the game, CD Projekt, says he couldn't believe his luck.

Mr Iwinski's business has sold seven million copies of the blockbuster series, but getting to a point where it could make money from it was as challenging as anything its team had devised for gamers to tackle.

Image caption Growing up Marcin Iwinski couldn't find computers and games in Poland

Playing catch-up

At high school Marcin Iwinski and friend Michal Kicinski were both passionate computer game players.

In the 1980s Poland was still behind the Iron Curtain, and most shops did not even stock basic foodstuffs, let alone cutting-edge personal computers.

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One Christmas Mr Iwinski's father brought him a ZX Spectrum from Germany along with early games like Atic Atac and Pssst. The young Marcin was immediately hooked.

Straight after high school he and Mr Kicinski began selling games they had imported from the US at Warsaw's computer market. In 1994 the pair moved into a small office and the company began to grow.

"A lot has happened since opening the country to the EU and it's more that people believed in themselves," Mr Iwinski says.

"Right now is the time when the entrepreneurial spirit of the Poles can show. It's definitely helpful there are good universities and the programmers are among the creme de la creme of world programmers."

Companies like CD Projekt and rival Polish video game producer Techland are among the most successful in the world.

Sinking the pirates

From the start of the business, the biggest problem for CD Projekt was how to convince Polish gamers to buy legal games instead of the widely available and cheaper pirated versions.

To differentiate themselves from the rest the company started translating every game they sold into Polish. They employed famous Polish actors to do voiceovers, and put a quality seal on each box.

Image copyright Pawel A Kowalski Image caption Designers are working on what CD Projekt hope will be their next blockbuster

"It was like an extremely well-translated book but with a voiceover, or dubbing," says Mr Iwinski.

The company made its games more attractive by including collectible bonus features such as books or maps. Budget versions of older classics were sold in supermarkets.

Mr Iwinski added that all this extra effort was an attempt to reduce the number of people buying pirated versions of its games, which are sold at flea markets across Poland, and see pirates wrongly put CD Projekt's seal of quality on their vastly inferior versions.

Slaying monsters

Both men had always dreamed about making their own game. In 2001 they created a software development unit.

They acquired the rights to the series of Witcher novels by Polish fantasy writer Andrzej Sapkowski, whose sword-wielding monster-slaying hero Geralt inhabits a Tolkienesque world.

"I still remember reading the Witcher story in a sci-fi magazine during high school. I didn't even dream that I would have a chance to work on a game based on the Witcher," Mr Iwinski says.

The game took five years to make at a cost of 22m zloty ($7.2m; £4.2m), an enormous amount for a Polish project.

Mr Iwinski says it has similarities to the TV series Game of Thrones in its grim medieval landscape that blurs the line between good and evil.

"It's not the usual candy-like fantasy thing. Previously almost all our PG games were candy-like, like Barbie World, you're the good guy, go kill the bad guy.

"Here we treated a mature audience with respect. It was something fresh, new and exciting for them."

CD Projekt now employs 350 Polish and foreign staff. It is developing a new game, Cyberpunk 2077, with echoes of the film Bladerunner, and the third instalment of Witcher will be released in February next year.

Mr Iwinski says: "During all this time the most important thing was our passion for games and the belief that we really feel what we are doing. Passion was fuelling us, we love what we do."