@white_fang Thanks for the help!
I under stand the set g_fScaleUIFactor. It resizes the UI in 2D, and a value of 0.5 is good for me. The issue here is that the I receive a mouse offset by half too. Anybody who knows how to fix that?
When using set g_nInternalUIResolutionMode I get the old UI, which is not what I want.