(Yes, that's big. If you don't want to suck the bandwidth, I am told that you can wait for the second expansion pack, which will be sold as a physical product at the end of 2004. It will include all the material from this download.)
For those of you who have been living in a hole in the desert... that is, who played in the Uru Live Prologue... I will now give the short form:
Uru: To D'ni contains just about everything that was put on-line, and a bit more. It has all of the Ae'gura city area (though not all available at first); two Neighborhoods; the Nexus; all of the Great Zero; someone else's Relto -- I won't say whose -- and a few miscellaneous rooms here and there. You can even get a peek inside a couple of Ae'gura buildings that used to be locked. But no climbing wall, and the Ayoheek table is no more. (Snif.)
...But most of you reading this don't know what any of that is. So here's the long version.
In Uru: To D'ni, you continue the exploration that began in the original Uru single-player game. The great public restoration effort has been cancelled. D'ni is supposed to be closed. But someone has placed a new book in your Relto, and this gives you access to more of the D'ni cavern -- areas which you could previously only glimpse from balconies and windows. And there are a few other changes to the areas you've already explored. (Important changes, I'll note. Be sure to wander around and see what's new. If you don't, you'll get stuck pretty quickly.)
The storyline of this expansion is not very complicated: you find your way into new areas, and bring parts of D'ni back to life. When you go as far as is goable, you hit a "To be continued" sign -- not quite literally -- and that's it. (Until the next expansion.) But Cyan manages to make this surprisingly satisfying. You find journals of people associated with the failed restoration project, and you follow along with their stories in its aftermath. You find evidence that you are not the only explorer in the abandoned city. And the discovery at the end -- which you attain in a nicely dramatic sequence -- leaves an appropriate sense of resolution. I wanted more, of course, but I didn't feel I'd been left hanging (as it were).
The integration of the material is interesting. It's not tacked on to the "end" of the original Uru. If you're starting fresh with Uru, you can install the expansion right off the bat, and you'll find it seamless. Material from the expansion will open up early on; you'll probably wind up playing the two storylines in parallel. They aren't totally independent -- you have to explore a fair way into the Uru Ages to find all the areas important for To D'ni. But you can finish the To D'ni storyline without having completed any of the Uru Ages. And vice versa, of course.
How large is To D'ni? Smaller than Uru, certainly. You do as much stuff, I'd estimate, as in one of Uru's four sections. Mind you, there's a great deal to see. The city area is huge. And spectacular; it all looks wonderful, and it feels even better. It's a terrific place to wander around. But it isn't packed with things to do. (The plot elements are mostly tucked away in smaller areas. Which also, mind you, look wonderful.)
On the other hand, if you didn't play on-line, you may actually spend more time on the expansion than you did on the original game. The longest challenge-sequence in To D'ni involves the Great Zero, and it boils down to finding goals hidden throughout the city (and outlying areas). Not solving puzzles to unlock goals -- just running around until you find them. And then, in the next phase of the challenge, you have to find more of them. And then some more. Remember how I said Ae'gura was a terrific place to wander around? You will wander around all of it. Repeatedly.
This may bug you or it may not. I like methodical exploration. (In Grand Theft Auto, I'm the guy who finds half the packages before the plot even gets going.) Careful exploration is part of adventure gaming, after all. And there are some non-hunting puzzles to solve. Even the goal-hunting takes on interesting puzzlish aspects towards the end. Overall, however, the searching-to-puzzle ratio is unusually high. Be warned.
Since someone is bound to ask: Yes, there is jumping in To D'ni. But much less than in the original Uru game. I count only three places where you have to jump at all, and only one of those requires any precision. Another takes some timing, but the margin of error is much broader than (say) the Gahreesen rotating catwalks.
And, while there are some objects to kick around, they're provided solely for your amusement. I think the beach-ball was intended as irony. Heh.
So what do I conclude? If you have broadband, but you never logged onto Uru Live, downloading this expansion is certainly worthwhile. It gives you more to do, more atmospheric streets to stroll through, more fancy shirts, more toys for your Relto, and -- I nearly forgot to mention -- a detailed history of the D'ni civilization. (Presented as a terrifying large collection of in-game journals. I haven't even begun to read through that material.)
If your Net connection is thin, keep an eye out for To D'ni anyway. I imagine it'll turn up on game magazine CDs, or other such sources. Or ask a friend to burn you a CD-R. If nothing else, it'll give you some idea whether you want to buy the later Uru expansions, when they appear.