Revelation has some amazing moments, but for every good moment there is a bad moment.
Another ten years have passed since the conclusion of Exile, and once again you're left to your imagination on what happened between then and the present. The game opens up with you on a tram ride with Atrus' now ten year old daughter, Yeesha. After a failed experiment by your good friend Atrus he travels to Rime (from realMyst) in order to get replacement parts. After exploring Tomahna and activating Atrus' backup power, you end up nearly killed when the walkway collapses. After you come to and find Yeesha missing, you must set out to discover what happened to her.
While the storyline itself doesn't sound bad at first; the execution of it was rather poor. The game is filled with cheesy dialogue, and contrived plot segments that just don't fit with the theme of the Myst saga. The story isn't by any means terrible. It could have been a whole lot worse, but it could have been a whole lot better too.
The gameplay in Revelation is more similar to Exile than to Myst and Riven. You are able to walk from one scene to another, and look around in any direction you want. Revelation like its predecessors also sports the same mind bending puzzles that are common in the series. Some of Revelation's puzzles can be a bit troublesome, however; particularly the Mangree puzzle on Haven, and the sound crystal puzzle on Spire. I'm also not particularly fond of the Dreamworld puzzle.
Revelation's graphics are probably some of the best in the series. While they don't reach the photo-realism of Riven; they come pretty darn close. A lot of time and work was put into the detail of Myst IV's worlds, and it shows. Haven is a thick jungle, Spire is desolate, and Serenia is bright and colorful. Each of these worlds (and Tomahna) have the same amount of atmosphere that is present in all Myst games.
Revelation's audio is great, for the most part. The sound effects are immersive, and the music is excellent though sometimes over the top. The voice overs and acting, however; are abysmal. Myst, Riven and Exile had fairly solid acting, but Myst IV is just plain bad. Even Rand Miller who reprises his role of Atrus seems to be a little off sometimes.
Revelation is a good game that has some issues in the story department. It could have had much better writing, but you can't change the past. Regardless of the plot issues, Myst IV is a must have for fans of the series, and a good a place to start as any for new comers.