Very few people want realism in fantasy, because it is too limited. You play game, because you want to experience something you can't see, do or imagine your-self in. Real life is boring :)
Actually, it cannot be totally realistic for sure, else it would become a ... space program. Still, I am convinced we can make an appealing game with the main real-life constraints of early planet colonization.
But as for the choice of time period, I find the close future much more appealing than the far future. It is easier to immerse into, and I expect that, in the years to come, the players could actually related there experience in the game to the events unfolding in real life.
Also, the period of the first pioneers is probably more exciting than the period where you manage complex cities. If you play Civilization, the first turns have a special flavour that you do not get anymore later in the game.
Realism in fantasy, sure.
Realism in S-F? Absolutely not! Start off with omni-present micro/nano/atto bots and proceed from this point anywhere you'd like.
That's pretty fun too (Rudy Rucker fan reporting for duty) but the complete lack of restriction can sometimes limit the creativity too, since creativity is often about solutions to problems, and for most problems to exist, there need to be constraints.
There's a good deal to be said for realist-ish sci-fi, as long as things are internally consistent, and there are some constraints to help both give interesting structures to the universe and society and to drive the plot forward.
But as for the choice of time period, I find the close future much more appealing than the far future. It is easier to immerse into, and I expect that, in the years to come, the players could actually related there experience in the game to the events unfolding in real life.
Also, the period of the first pioneers is probably more exciting than the period where you manage complex cities. If you play Civilization, the first turns have a special flavour that you do not get anymore later in the game.