The Legend of Zelda: The Wind Waker HD is pretty great, partly thanks to having a solid foundation to build upon. So solid, in fact, that it took an extremely short time to turn around. Producer Eiji Aonuma says the HD makeover took only six months to make.
"It took about 6 months," Aonuma told Zelda Informer. "Development was still difficult. You had to consider the difference in hardware at the time." He said that the original Wind Waker took much longer because cel-shading was a fairly new technique and the team had to learn about it, but now revising it is much easier.
The bulk of Aonuma's efforts went into reevaluating the second half of the game, since it wasn't as well-received. "That was my first time in control of the direction of the game and designing a game from scratch, there were some portions that I wanted to expand upon," he said. "If a remake were to happen, I believed I could work on some of those portions."
Nintendo started teasing the project in January, so if development only took six months, they started showing it off fairly early in the process. That would make sense, considering all we saw of the game at first was concept artwork and environmental stills.