Direct8 -> Direct11 converter:
http://forum.worldofplayers.de/forum/threads/1436307-D3D11-Renderer-f%C3%BCr-Gothic-2-%28alpha%29-13

Huge improvements, but if you don't have a modern graphics card (like me) it can really stress your computer. Whenever I turn on all features my FPS drops to roughly 12 FPS.

Graphics patch - L'Hiver:
http://forum.worldofplayers.de/forum/threads/1391645-L-Hiver-Edition-Grafikpatch-f%C3%BCr-Gothic-2
I didnt try out yet but you should be able to run the original game or other mods with it.
You can also get it as a single, seperated mod, but is has additional effects then.

I know, just a smashed up and rough guide, but I hope this was still helpful to you guys.