The Half-Life 2 "Mini-Series" remarks (Spoiler Free)
 

Ive loved Episodes 1 and 2 so far and Ive probably been more intrigued by the story as time goes on. Yet there are still two areas that Id love to see revisited

Xen and Black Mesa

In regards to Xen, I think it would be facinating to go back there now that they are free from Nilhi...whatever's (read as the Combine) control. Personally I could see nothing more enjoyable then watching the combine army get riddled with hornets from the Xen Grunts

Black Mesa would also be cool to revisit, not only because it would look simply stunning with the new graphics, but because after the years its been abandoned in its ruined state, it would be pretty cool to see whats lurking in there now. Especially if they made you re-enter Black Mesa through that cliffside tunnel from Surface Tension (That level still gives me the creeps, Im not scared of hights in real-life but something about that level just gives me the willies)

Id say the Combine Homeworld too (Whatever it may be called), but something tells me that it will be a feature of the final episode (whatever that number may be). But Im not going to hold my breath on it.

Well, I don't know about the Combine Homeworld, or XEN, but there is a mod coming out for HL2 that is a complete remake of Half-Life 1, in the Source Engine, called Black Mesa. Also, as for coming back to Black Mesa...

SPOILER It was destroyed when a nuke was set off by the G-Man an the end of HL. The radiation would have killed of all surviving life in Black Mesa afterword. So it is impossible to go back right now. SPOILER

Well, there you go.

Xen was taken over my the combine, but I guess that might be able to, although in Ep.3 you have to do something about a ship (at sea) called the Borealis.