Space colony was ok, it was just horribly designed, and put together like a cross between <anything> Tycoon and a more limited The Sims.
I played outpost as a kid, except I was a kid and had no fucking clue what I was trying to do, and I don't remember anything but its basic premise.
It probably is a hard thing to get right. If you're going for a hardcore peaceful simulation of developing means of agriculture and industry, then it's just something like SimCity, only in space with gimmicky, alien building blocks (you can relate to a highway, or a block of housing, but a bit less so to hermetically sealed tunnels linking blocks of similarly sealed flats). If you go for a more militaristic theme, trying to colonize a hostile planet, then it's... what? Probably just one out of a number of different archetypes, but TOTALLY IN SPACE WITH ALIENS AND SHIT! :/
As compelling fucking awesome as the basic idea is, there are only so many ways you can take it, and they've mostly been done before, and even if you managed to outdo them gameplaywise, it would still be seen as gimmicky and derivative, in all likelihood.
I have ideas on it (as does everyone and their mother, presumably), but they all fail the above problem, and I have better ideas for other things, in any case. If only I could be bothered to concentrate on them long enough to actually ever do anything...
The SimMars thing was depressing because it showed what Maxis was, which stands in stark contrast to the pile of shit they've become under the heinous leadership of EA. Kind of like looking at what Relic's become, or Bioware. I hear Blizzard used to be good too, before Satan himself took the helm.