This page is for the 2014 game. For the original 1998 game, see Thief: The Dark Project.
When Health, Focus, Ammo and Inventory are set to "Timed Fade" in the Game & HUD menu, they only fade to around 50% opacity. This fix will make them completely disappear after a short while of inactivity, relieving the HUD of clutter.
If the "Exclusive Fullscreen" setting is unchecked, the visuals will be one frame behind your input. You can fix this by either checking "Exclusive Fullscreen" in the game options, or by disabling "one frame thread lag" in the configuration files like so:
If this doesn't help, see "High frame rate" above.
If the game is on an external drive, voices, subtitles, music, and some sound effects like lightning may not play during the game. This can easily be observed in the prologue cutscene, where Garrett should be speaking. If you installed the game on an external drive, try moving it to an internal drive (it does not have to be the C drive).