Surprisingly it's the last screenshot that's really gotten me - especially that... whatever that thing is... on the bottom left, and not the ships.
Somehow I kind-of feel that, to really capture the Homeworld universe, there needs to be a lot of play on the backgrounds. Probably just me though, but from what little I played out of HW2 (never played the first), all the cutscenes and some of those places where you have those mysterious giant installations as part of the background...
The feeling of mystery in a really, really deep and dark sea of space. That gaping white hole... just what IS behind it? It looks like a place you can go to, yet you know you can never really "go there".
That... is Homeworld.
At least, to me anyway XD