PC programming whiz John Carmack sees a big future in cell phone games, but a lurking disaster too. He spends two days a week building rocket ships. His idea of a getaway weekend consists of holing up in a hotel room and writing programming code. And he likes to speculate on worst-case scenarios for the video game industry. These days, though, cell phones are his primary hobby - specifically making games for them. It started as a lark, he said, but it has become something he quietly hopes will revolutionize gaming.