End of Ages's gameplay consists of navigating worlds known as "Ages" via the use of special books which act as portals. On each Age, the player solves puzzles and discovers story clues hidden in the Ages. The player's actions in the game decide the fate of the ancient D'ni civilization. In a departure from previous titles in the Myst series, End of Ages replaces pre-rendered environments with worlds rendered in real-time 3D graphics, allowing players to freely navigate the Ages. (wikipedia.org)