I think-

Half Life 2 was good because it had a good aesthetic,
well designed, buildings, vehicles, people,
all created a good atmospheric post appocolyptic Eastern European city.
It all had its own look.

Doom 3, sorry, it looked like Aliens interior, industrial space age interior to
me. Even Red Dwarf.

Matt, thanks for your detailed reply about Sphere. I would like to look into buying it, I need to see if I can turn things off such as the soft shadows etc.
That may help with the frame rate reduction? Can I try this in your demo?

To get back to the topic, nice screenshots again! It will be interesting to see if you get shaders in it too.