There was one excelent disaster/economy colony building RTS called Outpost 2.
Just wanted to aside to give props where props are deserved. Outpost 2 is incredibly underrated, and did a great job of salvaging its poorly-rated-and-deserving-it precursor. The single player campaign had some pretty amazing and frantic player-versus-environment missions with no combat. It's incredibly dated now, in that awkward early-Windows-9x era that's so hard to get compatibility to work with, but if you're okay with doing a bit of archaeology I recommend it as a neat piece of overlooked RTS history. Also it came with a surprisingly compelling novella; the story was about on par with Alpha Centauri's world building.
I might be looking back with some very rose colored glasses, who knows...
Speaking of combat though, Malkari is another game archaeology case from the same era. Fabulous idea for a 4x, terrible execution, but the whole game was made with simultaneous-plan, simultaneous-execute turns. It might require a VM to run, it was a hack and a half even when it was new... but I keep wanting to mention it whenever people talk about novel ways to handle combat turns. That, plus the surprisingly thought out ship designer and research system, and not too shabby faction differences, is really worth looking into if you nerd out over that stuff. (Maybe track down the manual and read that instead of trying to play it.) I wish the lead designers had been given Sid Meiers' or Will Wright's implementation teams because there was some brilliant stuff. Maybe if they'd given it another year in the workshop; the company closed its doors pretty soon after it came out, so I imagine what came out just wasn't finished.
