In Megaton they managed to use a yellow TTF font for the menu while on the loading and level ending screen they still used the red font. Primarily however I would be interested in recreating the
EDuke32-style HTTK HUD with its semi-transparent yellow icons, transparent keycards and yellow numbers. TBH I think it's pretty cool and even better than the current EDuke32 HUD from a visual/artistic POV.
I dunno if this can be done however since graphics are created from sprites and you would have to make the HUD use its own icons somehow. It would work for the inventory icons, but not for health/armor/ammo/keycard symbols.