Oscar-winning actress Lupita Nyong'o lost her heart in Uganda. The Kenyan actress was in Johannesburg this week for the premiere of her latest film, Queen of Katwe. The film is based on the true story of a Ugandan girl's pursuit of becoming a chess grandmaster.Based on the life of Phiona Mutesi, Nyong'o plays Phiona's mother, Harrieti, whose daughter went from the slums of Uganda to become a candidate master after her performance at the World Chess Olympiad. Speaking to the media yesterday, Nyong'o said it was the "magic of real life" that drew her to the film."I saw a complexity, layers and really interesting, relatable character and on top of that it was African. It was an oasis in a desert, nothing like that had crossed my desk until that point."I was so excited to finally tell a realistic, passionate and enlivening African story," she said.But it was her fellow cast that stole Nyong'o's heart. The young Ugandan actress Madina Nalwanga, who plays Phiona, and the other kids in film have been on the Hollywood star's mind."Bonds were formed while making this film. My heart exploded for the children that I mothered in this film."I do not stop thinking about them. I definitely want to avail myself to them as they grow up," the actress said.Directed by Mira Nair, the film was partly filmed in Uganda and Johannesburg.Queen of Katwe shows young Phiona's determination to escape a life of poverty and save her family.Nair said: "There's genius everywhere, that is the point of this film. We all have something to say, you just have to find a way to say it."Nyong'o added that she could identify with Phiona's story. "This film was about a small girl with a big dream who achieves it."..