nicolascy: REMEMBER BEFORE PLAYING DUKE 3D and UNREAL :
THAT FOR DUKE 3D FANS MADE THE AMAZING HRP -WHICH STANDS FOR HIGH RESOLUTION PACK.You must download a program called Eduke32 that is a new direct 3d engine that also supports some wicked colored lighting,antialiasing etc.. And then download the HRP that is around 600-700 mb
For Unreal there is a new unnoficial patch the 227h and there is also a new dx9 and dx10 render-(For dx10 you need to play unreal under vista or 7 ) and there is also a ENBSERIES HDR pluggin.And last but not least there is a high definition texture pack.
I messaged gog about the above to incorporate them or at least provide links for users to download them but they did not responded......In any case playing under dx9/10 with HDR and high resolution textures is like night and day than playing it stock.
They only sell original copies, and they already added links in the Duke Forum.