I have a sci-fi setting which I've not had the time to design yet. It's a distant planet that's been colonised 300 years ago. The terraforming project is still in its infancy and there is no breathable atmosphere, everything is mostly rock, sand and ocean, except for human settlements and mining operations. The human population is relatively low.

The thing I personally find interesting, design wise, is that the planet has no fossil fuels, and thus there can't be things like plastic. It also doesn't have any forests, except for what's been planted to help with making breathable oxygen, so wood is basically a luxury item. It's literally cheaper to buy a desk made of solid gold than one made of wood.

And so there's no such thing as plastic bags or paper bags (or any paper at all!), and I've been having fun thinking about people carrying around aluminium bags instead :P

In any case, my main ideas for that setting are culture-related, but the stuff described above would be the design challenges. Sci-fi settings tend to often look like everything's made from plastic, so being forced to use only metal, glass, ceramics, etc. might generate some interesting results.