Quote from this is the clownDisplay MoreEmailed Valve about Custom Content "Please try to use HL2 assets only when creating your map. This includes
textures, models, etc.
Maps which use non-HL2 assets will still be considered, but our judging
process will favor maps which stick as closely as possible to assets in
HL2."
but i think i'm just gonna stick to HL2's props and textures to be on the safe side.
They mean that now, but not later. When judging begins, the judges will be so sick of the same textures/models that they will lean towards custom content.
I hope you people trying for this dont put exploded car props in your maps.