Awesome game. I played this back in its release year. I'm not sure if that was a good choice though, because of my age at the time, I looked at a bunch of walkthroughs, and therefore spoiled a bunch. :P
Regardless, even after being 10 (11 for non-expansion) years old. This is still by far one of my top 5 favourite games of all time!
The reason I don't have many play hours is because... well, I've played it a hundred times over before it even came to Steam. :P
This game has many many abstract worlds, mind boggling puzzles, a very unique style of gameplay, and so much more!
Despite Cyan still updating the Uru: Live (free online!) version of it, I'd really like to see a new game similar to this with improved physics, graphics and such. They did attempt to change physics before with the current game, but well... to many things broke for them to keep it, and despite being so old, the grahpics are still very good for it's time, and it is almost gaureteed to not even lag on newer systems that are crap!
Anyhow, that's besides the point. If you love adventure-puzzle games, you should really check this game out!