The latest version of TFix, which modifies the Thief TDP or Gold installation, may be found here:
The instructions described below were developed several years ago. These steps still work, but a much easier method, which achieves better results, is to use a user-developed program called TFix, which is described on page 2 of this thread. TFix takes care of all the problems with video, audio, multiple cores, and wide screen in one installation. You start with a fresh install of T1, run TFix, change a few configuration settings to your liking, and that is it. Further details are given on page 2. Enjoy.
Thanks to John Curran for pointing this out and providing detailed information on his web site, http://www.johnanthonycurran.com/thief.html.
Obsolete instructions below
The purpose of this thread is to list verified fixes that are necessary to make Thief 1 (The Dark Project or Gold) run on modern computers (Windows 2000 or later). Please do not use this thread to ask questions. Please start another thread for questions. If you find any errors in the following or suggested improvements, please post them here.
There are several things one generally has to do to get Thief 1 to work on a modern computer. Some depend on the type of video card you have, as noted below. Some depend on which version of the software you have.
1. Installation. Install using the normal method. A full install is recommended. Disk space is cheap these days, and you don't want to be reading files from the CD during the game.
2. Patch. Start Thief but do not start a mission (the main graphics). Escape to desktop using the Pause/Break key, and look at its icon in the task bar. If it displays a version number less than 1.33, it would be a good idea (but not necessary) to patch the installation to version 1.33, the final version of The Dark Project. Thief Gold is the final official release at 1.37, but if you do not have Gold already you cannot patch to Gold.
For original release versions, the patches can be found here:
If you have a re-released version, it may be already patched. If not, you need to get the patch from the software manufacturer, not the above link. It may be on your CD.
3. convict.osm. To get Thief 1 fan missions to run, you need to download the file convict.osm and place that file in your Thief install folder. A link to convict.osm is found in the above patches link.
4. Single processor. If you have dual or more CPUs, or if you have hyperthreading enabled, you must make Thief run on only one processor.
First test it with Process Manager. Start Thief but do not start a mission. Hit CTRL-ALT-DEL and select Process Manager. Select the Processes tab and scroll to find thief.exe. Right click on thief.exe, and set its affinity to one CPU. Then return to Thief (icon on task bar), start a mission, and play for a while. If it works, then make a backup of your EXE and make it permanent using imagecfg.
5. Correct Nvidia driver. If you have an Nvidia video card, note that many Nvidia drivers cause an immediate crash to desktop the instant you start the main Thief graphics. You need to install one of a few drivers that are known to work with Thief 1. As of this writing, April 14, 2008, the following are known to work: 163.71, 163.75, and 169.21 WHQL.
6. safe_texture_manager bug. If you have an Nvidia video card and one of the original Thief releases, you will probably have a problem with the safe_texture_manager bug, with which you will see an error "Direct 3D Device does not accurately report texture memory usage". Unlike Thief 2 there is no line in USR.CFG to fix it. Instead, you must download a patched EXE in which this problem has already been fixed. See the section "Nvidia Driver 5x.xx Fixes" in the patches link, item 2 above.
If you have a re-release, particularly one stating that it stated to be compatible with XP, then the above patches will probably not work. If that is the case, and if you can't get past the safe_texture_manager bug, then your only solutions are to use an ATI video card or to ask for your money back from the software vendor.
7. DDFIX. After you get it working, consider installing the DDFIX patch for 32 bit rendering and no resolution switching with menus and books.
You will not see an obvious benefit in the rendering with Thief 1, but you can see that it is smoother if you make a screen copy and zoom closer. Its main benefit is to avoid the resolution switching.
I suggest that you try to make Thief run before applying DDFIX, because there may be other problems that need to be solved first. If you have issues making DDFIX work, there are probably solutions posted at TTLG:
8. For some recent Nvidia cards (e.g., 8800 GT), you may have to install DDFIX before it will run.
Vista? There may be some additional things you need to do with Vista. I am not currently aware of them. Please respond with any additional fixes you find necessary and successful. I'll add useful ones to this initial post.
Re-released versions. There may be additional problems associated with re-released versions such as Sold-Out or Steam. I am not currently aware of these problems or how to fix them. Please post any additional fixes you know will work. My advice is to stick to the original release versions if you can find them.