Thread:Deathstalker666/@comment-24111404-20141216005515/@comment-3547390-20141218020901

First, you need to complete Thief Gold before trying Thief 2. The two games are meant to go with one another.

Second, ignore Raadec's beliefs and go Garrettloader. It has a bunch of built in tools that reset things that otherwise mess up and whatnot. Now, I can't guarantee it working with Steam (similar to the problems with had with Quake), but its worth a try.