EDIT: I deleted my first paragraph somehow? Ummm...well ill just leave this:
Central Question: "Will this make my game better able to achieve its goal?"
I think that is the central question of game design, and one that is often ignored for the sake of adhering to trends. Regenerating health has its place, but it seems like every FPS these days has Regenerating health. Why? Well because it is the popular thing to do.
This question should also be asked when designing an area in a foreign world like you are talking about. Would making the world look significantly different than earth and leaving the potential for the player to be confused make the game better achieve its goal? In many cases, I'd argue yes, but once again, this question needs to be asked for all games, and there are times when an "earth-like" planet may be best.
I have never made a game (although I have thought about it for a long time) but I think that in pre-production, this central question needs to be asked about every system in the game. Many video games seem to take the central layout of a popular game, tweak one aspect and call it brand new, even if all the other pieces don't really fit to the ideology of the central idea.
