Khaled Abdulgader noticed children using an unusual object as a football and tried to stop them. He grabbed it, and it exploded in his hand. He lost two fingers, and shrapnel sliced into his chest. In a hospital for a checkup after last year's blast, he tried to stay positive. “I feel like, ‘Thank God it was just my hands,’” Abdulgader said. He is among hundreds of people who have been injured or killed by unexploded ordnance in Sudan's three years of war. That includes mines as well as weapons such as bombs, shells, grenades or rockets that failed to detonate, tens of thousands of items in all. The government and aid groups say it's a problem particularly in and around Khartoum , where residents, many unfamiliar with the threat, have started to return after the Sudanese military recaptured the capital last year.…