That doesn't mean it was easy
Nintendo's recent remake of The Legend of Zelda: The Wind Waker HD was one that had fans giddy with anticipation. Luckily, that anticipation didn't have to last all that long, because according to the series' producer, Nintendo turned the entire project around in about six months.
In an interview with Siliconera, Eiji Aonuma revealed the considerably short development time, but didn't discount the amount of effort that his team had to exert. Aonuma stated that "development was still difficult. You had to consider the difference in hardware at the time." He continued "there is a technique known as toon shading, which gives the game a very animated look. At that time, the technique was established, but had not been used before by our staff, so everyone had to do everything by hand."
However, it may have been the widescreen support that proved the most troublesome in preparing the HD version. "For dramatic purposes, we would have characters we didn't want in the frame, but in 16:9 ratio, you could still see those characters," Aonuma said. This meant that the developers had to manually edit all applicable scenes.