From the interview with gabe newell:
Could you inform us of what the maximum "acceptable" polygons is for both levels and models?
That's really an art and design issue more than a technical issue.
From that answer i will belive that the source engine has no polygon limit, only the video...
I just had to make a simple 3d render with that image =)
I edited the image and made a bump of it..
I'm no 3d guy, and the bumpmap is pretty simple..
sorry for the high res images, but i feel that it was the right size to render =)
(i will be playing hl2 in 1600x1200 :p)
Edited image...
I would just say that hl2 suppoert 2k x 2k textures. (2048 x 2048 pixel)
it support a new texture system\pack.. where mappers can include their own textures.zip into the map file.
I hope the new textures are jpg or some multilayer textures that can be made in photoshop.
The max polygones...