For one reason or another, Jade Empire is the one BioWare RPG that didn't really catch fire. It went over well with reviewers, but just couldn't find enough of an audience to merit a sequel. Perhaps that will change in the relatively near future, as it is now free on Origin.
As is always the case with Origin's "On the House" giveaways, the Jade Empire freebie is a limited time offer, and it's for the full version of the game—technically the "Special Edition," which is what publisher 2K called the PC version of the game that came out a couple years after the original Xbox release. It features enhancements including improved graphics, new monsters, enemies, and fighting styles, better combat AI, a new playable character, and other bits of goodness you can read about at the Jade Empire Wiki.
And it's free, and yours to keep until the end of days (or end of Origin) as long as you snag it before the offer ends. When that will happen is anybody's guess; EA doesn't specify a wrap-up date on OTH deals, which I imagine is supposed to make it all that much more exciting and fun.
Despite my optimism in the opening paragraph, I don't really expect that this will ultimately represent the first step toward a Jade Empire sequel. It's been more than ten years since it was released, after all, and between Mass Effect, Dragon Age, and Star Wars, I think BioWare's hands are pretty full these days. Then again, dare to dream, right? Even if that dream is only, "Gosh, wouldn't it be nice to play a BioWare RPG that isn't part of a major, heavily-sequelized franchise?"
Get your Jade Empire freebie here.