Alan Moore interview
The success of Swamp Thing led directly to Watchman, illustrated by Dave Gibbons, is a superhero tale set against a doom-laden holocaust fomented on the inside from one of their own members. I'll admit that it does resemble some of the plot from one of the old Twilight Zone episodes, Architects of Fear, but Watchmen, like most of Moore's output, is densely layered, ambitious, and greater than the sum of its parts.
He gone own to create other works, but prefers doing things by his own terms and pursuing his own interest as well. Here's a recent interview. Scroll down the page to read it.