A large fleet departs from a nation due to *plot*. The players are either the officers (and captains) of the flagships (but not the flagship), or people who work under them. They are to bring about the success of the colony(s) in a forsaken world...
Fantasy, incidentally, not sci-fi or steampunk.
Interesting.
(1) Making two threads, one the officers and the other more mundane people. -> probably can't work for numerous reasons......
Not sure I see the point.
(2) Making the officers also be heroes of sorts, having extraordinary abilities. Such as magic.
I would have thought that'd be a given, at least in the cases of officers who aren't incredibly good warriors or similar instead.
(3) How many players? o_o
Depends on how complex you make it. Without knowing anything about the system, it's impossible to know the idea number for gameplay or GM sanity. Six makes a nice default, though.
(4) Having the game setting be not the physical world, but another plane. Such as the special place of Runners of Hyperion (I think) . ((I wonder what happened to that game...))
Sounds good. Having an excuse to throw anything you like at players can be handy.
(5) How would I keep the game from being a complete 4X game? XD It seems to simply demand itself to be so!
I fail to see how this is a bad thing.
OH! You mean for your sanity in actually tracking and balancing all this stuff. Erm, just abstract it, and if necessary abstract it to the point of not existing anymore. Research could just be a simple "order our researchers to find this" as opposed to specifying amounts or whatever, and they could make breakthroughs at set intervals or arbitrary dramatic moments if rolling for it or accumulating points was too tough. Worst case, you could even say that research is assumed to be going on, but only really breaks through when you actually put it into practice, which is a polite way of saying it doesn't exist but you'll let people do or have things they didn't use to after a while.