[Zhiroc]

I'd have to recommend "Firefly"-themed worlds as probably the most hard science-fiction game environments (in the non-original theme category). However, it ends up sharing a lot with a Western theme as well. And as for "hard", I've never quite understood the solar system it is based in, to have so many accessible worlds without an FTL or at least extreme-speed drives.

I'd usually include Star Trek, and any new Battlestar Galactica settings as mostly hard science fiction. I agree that time travel, psychic aliens, and holodecks just about cross the line though

Of course, the main reason for things like teleportation and FTL is literary, particularly in the light of a movie or TV episode--it lets the story move along. A book isn't quite so constrained, but still usually needs FTL so you can get to other worlds in a "reasonable" time. However, what really gets me at times is when the story becomes inconsistent. If it takes FTL to get between worlds, and the FTL breaks down, "limping" home using sub-light just does not work. Even in a solar system, you'd probably have to have an almost lightspeed drive to get anywhere before you'd run out of consumables (a ship designed to reach a port every so often is not going to stock enough food to last 10x the expected run).

As for where things cross the science/fantasy border, it's hard to say. I guess I'd probably choose whether or not it's done using technology. Teleporting using a transporter is OK. Using some psychic/magic/non-technology method is not (e.g., "flinging" if you ever read that series of books). This is just a reference to hard vs. fantasy, btw. I don't dislike science fantasy as a story setting just because it is was it is.