This is easily one of my favourite games of all time.
A story-driven RPG, with the usual Bioware morality scale, only far less black-and-white, good-and-evil, and more to do with the actual ethics of characters, rather than "GOOD GUY HELP EVERYONE AND FART RAINBOWS, BAD GUY EAT PUPPIES AND SET EVERYTHING ON FIRE". Think Star Wars (Especially since this came out around the same time as they were working on the Knights Of The Old Republic games), the 'Open-Palm' path is basically the Jedi to the more Sith-like 'Closed-Fist'.
I may be slightly biased due to my love of martial arts and mythology, but this game is rich with both, so I don't care, it's great.
It's basically like being the major protagonist of a fantasy, kung-fu, cult-classic movie, for 20+ hours. There are demons, spirits, gods, ghosts, assassins, pirates, heavenly plains, and so many other things that I can't mention without spoilers.

There are a lot of comments and reviews and whatnot for this game saying that it's not playable, or it's broken, and that it's all Steam's fault everyone is awful wah I'm a big whiny man-baby.
It's not broken. If you're not an idiot. This game is nearly a decade old. It needs a little help to be able to run on newer computers.
If you're on Windows 7, you will need to go into the game files, right-click on the "Jade Empire" application, go into the compatibility settings and set to run with Windows XP compatibility. There, I fixed it, now stop complaining.

BUY IT. PLAY IT. IT'S GREAT.