While Angry Birds is still the top paid iPhone game, a game written by an eighth-grader has spent the last few days atop Apple's free charts.Bubble Ball, a physics simulator, was coded by Robert Nay, a 14-year-old from Spanish Fork, Utah. The game challenges players to use objects and gravity to guide a ball to its destination. Nay spent the better part of a couple of months writing the game, which debuted in the App Store late last year and is also available for Android devices. In recent days, though, it has been rivaling Angry Birds Lite atop the list of most downloaded free games. "I was pretty surprised by how well it was doing," Nay told Mobilized. Nay said he plans to add more levels to the free game and then eventually add still more games as an in-app purchase. He also has some other ideas for games he'd like to write down the road. Although it's his first game, Nay has been into computers for some time, including Web programming and helping others with their computers. When he's not at the computer (or school) he also likes reading, especially science fiction, and playing the piano and trumpet.