DISCLAIMER: I did not make any of these modifications, I merely found a working configuration to get the game looking and running as great as possible.

Following these steps will get your game to look as good as possible while actually increasing the game's performance on modern systems.

Be warned, this may not work on every computer as DX11 for Gothic 1 is still in development, although compatibility has improved in recent times.

To have the best chance of it working be sure to follow these steps exactly. Step 6 is the only step you can skip, but without it your textures will just be default. Do not skip any other steps or your game won't run at all.

If a link is broken you may need to google for a mirror of the file.

Link: http://www.worldofgothic.de/dl/download_6.htm
This is the official latest patch for the game.

Link: http://www.worldofgothic.com/dl/?go=dlfile&fileid=28
The player kit allows you to run mods.

Link: http://forum.worldofplayers.de/forum/threads/1340357-Release-Gothic-%C2%BD-%C2%97-SystemPack-%28ENG-DEU%29
Download the 'Gothic 1 Classic' version of the System Kit - the downloads section is at the bottom of the first post.
The system kit modifies the engine to allow many modern features such as high-res support, widescreen, higher render distance, removes FPS lock, etc and is required for most mods.
I usually recieve an 'unsafe file' warning from my antivirus whenever I download System Kit installers (especially when there's a new release), but have never had an issue once installed.
If you're not comfortable installing the system kit because of antivirus warnings, then don't install it, however the DX11 mod will not work.

Link: https://github.com/Kirides/GD3D11/releases/download/v17.7-dev11/Gothic1-GD3D11-17.7-dev11-fix2.zip
This newer version of the preview release is made specifically for Gothic 1 and does not require any additional files to get working as was the case previously.

Link: https://www.worldofgothic.de/dl/download_553.htm
This is 'Riisis Texture Mix 1.1', you can try other graphics/textures mods if you like, but this one definitely works with everything else in this guide.

You can bring up the DX11 menu in game with F11 or Control+F11

These are some of the graphical issues you may encounter while using the DX11 mod:

• You may occasionally get a black screen after playing for a little while, sometimes while saving your game. Don't worry if you were saving your game when this happened, this is not a crash so your save data will be fine, but the game will need to be forcefully closed and restarted.
  
• Some of the trees have incorrect collisions and you may walk in to invisible walls when walking near certain trees, but I didn't find this to be too gamebreaking or annoying, just something to be aware of.
  
• In underground levels such as mines and temples you may get a really annoying bug where you're able to see through walls at a certain distance, but not when you get closer. I'm really not sure how to fix this.
  
• Some players have reported that when it is raining in game, save files can get corrupted. If you want to ensure this does not happen, you will need to set skyEffects=0 in your Gothic\System\Gothic.ini file - however this will mean you have no rain or other sky effects.

As I mentioned, you may not be able to get this to run on your system, but before you give up, try these things as they have helped some people:

• Unplug/disable all but your main monitor.
  
• Even though you are running the executable, try disabling Steam overlay for the game.
  
• If the game crashes on load, try it again, it may just be having trouble with the intial resolution.
  
• Be sure the game is running in your native resolution, both in the gothic.ini file and in the in-game options menu.
  
• Windows 10: Install the game in an other folder than "Program Files"

- Added link to Riisis Texture Pack 1.1


- Added link to the updated DX11-Mod 17.6.7 (Thanks .subnet).

- Added link to the updated DX11 preview build for Gothic 1 - working far better than the previous solution! (Thanks iGooseman)
- Removed step that required use of Gothic 1 drawdll as the new Gothic 1 DX11 mod does not require this.