Thief Gold is an updated re-release of the 1998 title, Thief: The Dark Project. TDP helped shape games as we know them today, and is often called the grandaddy of modern stealth games. If you can look past the dated graphics, this game (along with its successor, Thief: The Metal Age) remains the purest stealth experience available on PC.
Pro Sound design enhances stealth gameplay
One of Thief's grandest achievements is its dedication to sound design as a means of stealth gameplay; other stealth games are often set in the third person perspective, allowing players to swing cameras around corners, cheating their way through a level. Thief instead emphasizes sound. Walk on a marble floor or metal grate, and you're likely to make some noise. Creep across a carpet, and you'll be quieter. This works for the guards as well, so you can listen for them pacing on the other side of a doorway, but watch out! If there's carpet on the other side, you might not hear them coming. Thief uses this mechanic in a wide variety of ways; you can use arrows that sprout beds of moss to avoid detection, for instance.
Con Stock controls are not great
Before jumping into the game the user will most likely need to set up the controls in settings as the wasd controls do not allow movement from side to side when first starting the game, while this can be adjusted, it is a pain to have to do this from the get go.