realMyst: Interactive 3D Edition was a remake of Myst released in November 2000 for Windows PCs, and in January 2002 for Mac. Unlike Myst and the Masterpiece Edition, realMyst featured free-roaming, real-time 3D graphics instead of pre-rendered stills. Weather effects like thunderstorms, sunsets, and sunrises were added to the Ages, and minor additions were made to keep the game in sync with the story of the Myst novels and sequels. The game also added a new Age called Rime, which is featured in an extended ending.
Source: Wikipedia, "RealMyst", available under the CC-BY-SA License.