A lot of gamers feel the same way about Carmack's past work. He's the co-founder of and the genius behind some of the biggest titles in gaming, including Doom, Quake, Wolfenstein 3-D and many others. His engines have been used to create other award winning titles such as Half-Life, Call of Duty, and Medal of Honor.d"

But recently, his considerable developing talents have been focused on the iPhone platform. In many ways, this is a homecoming for Carmack--some of his earliest and best work was on the old Apple II.

Still, since that initial success, Carmack has returned to the Apple platform only sporadically, including a period of development for Quake 3 and when OS X first launched. The relationship between Carmack an Apple has always been a bit tumultuous, as the developer has often criticized the company for its gaming support.

But Carmack took an immediate liking to the iPhone platform, after testing ports in what began as a casual project to satisfy his curiosity. When tinkering with some early ports, he says that he realized: "Hey, this is easy and fun." A new venture was beginning.

Carmack's first major port for the iPhone was . During the development phase, the seasoned veteran admitted to learning a lot about making games for the iPhone. Carmack found speed optimization opportunities during the development that really helped for his later port of Doom. Effectively, these innovations allowed Carmack and company to "more than double [Doom's] speed." Carmack admits the biggest challenge for Wolfenstein was the control scheme. "We didn't feel we could a good job with a first-person shooter."