I was a big Riven fan but I never tried URU so far - this seems like a great chance doing that. Could someone sum up what the multiplayer experience is like? I could never really imagine how this works. Are there puzzles that you solve together, something like in Portal 2?
Most are 'exploratory' (they can be solved by just one person who does a lot of backtracking / note taking, but are easier with two)
A few actually require two people. (I can't remember if they are still in MOULa today, or if their one-player counterparts are live).
A few are "cheat" puzzles -- they rely on the (very bad) physics engine or stupid-long wait times. (some are upwards of 20-30 minutes, some are over 24 hours). They were always bad ideas, but luckily these are few and far between.
While I'm a big fan of what they were trying to accomplish, the experience is significantly less polished when compared to Portal 2.
If you found Riven enjoyable, the puzzles are slightly easier and simpler. You'll probably have fun, either on your own or with a few friends.
Most of the puzzles are solvable by a single player, because the original Uru Live got cancelled before release, and they had to re-work things to create a single-player offline version. The only puzzles that strictly require a second player are in content introduced during the short-lived GameTap revival. However, may of the puzzles that are theoretically solvable by a single player were first solved by group effort of observing and mapping out the new worlds.
Uru's single player mission has incredible high-def graphics that still look great today. The geometry is obviously a bit limited, but the textures look great even at 1920x1200
