Specifically, I tried Jade Empire: Special Edition on Steam.
I just tried it for a few minutes, but everything seems to work, even cutscenes and battles. The problem is that the mouse is never visible. I think this is normal during gameplay, but I certainly expected the mouse when navigating the menus.
I think the game is entirely playable, just a bit annoying to fiddle with the arrow keys when you need to attend to the menu.
There's one other little bug. Launching the game. I could not run it directly; it had to be done only from Steam, and only through the "Jade Empire Launcher," which actually starts playing the music several seconds before you actually see the "Play" button. (So it would be a pain to try to debug this version!)