All depends on how well done the game is.

Typical sci-fi setting is as bad as typical fantasy setting and is as bad as typical 'realistic' setting. Don't you see that aliens are just the same guys who played orcs in other game?

Don't forget Mass Effect.

Ah yes how could i forget that masterpiece.

If you are counting a game like Ratchet and Clank as one of those BAD, time travelling, jumping 40ft in the air, shooting ugly aliens with nerf guns, sci-fi games then I renounce you utterly.

But if you are talking about sci-fi games that are done in a realism style and take themselves too seriously while hitting all (and I mean ALL) the classic sci-fi tropes, then we might have a point of agreement.

What's Valkyria Chronicles? Is it Sci-fi? You better not be layin' the smackdown on the VC.

Any setting or theme works if done well. But really, Videogame technology allows infinite possibilities. We can overcome what is simply real to make anything possible. Fantasy worlds we could never imagine are there for us to enjoy.

I just don't get why, with all this possibilities for magic and wonder, people want to stick to games that duplicate the normal and real. How Why do I want my escapism to be plain?

I don't know many games that completely imitate life.

Uhhh.... maybe Pong if we build giant levitating blocks.

Shenmue but some critisize it for being boring as a result.

@OP: This game conforms to everything you listed that you dislike (alien enemies, takes place in the future, on another planet, unrealistic guns) and is unbeliveably awesome. Maybe what you meant to say is that you dislike bad sci-fi games.

Depends.  Most Sci-Fi games are the same as the rest.  But there are a few exceptions.  For example, Mass Effect was one of the few games that really pulled me in emotionaly.  I've only been more drawn into a story by FF VII and MGS series(Especially 4).