Eventually I'll get around to doing a full review of Survival Project, since I've read most of it, but in the meantime yes, I would say that your prose definitely tends towards the labored. I think Dragonfree left you reviews to that effect on the story as well; you might go back and see what she says in them, too.
Your writing definitely gives the impression that you're trying hard to be poetic or deep or figurative or something; if that's the case (i.e. if you're sitting around thinking, "Hmm, how can I put this cleverly?" or, "Wow, this is a really cool metaphor, I'm awesome!), then stop trying. When someone makes an effort to sound sophisticated, it strangles their real voice and turns the resulting prose into dull, stilted sludge. If you're not trying--if the prose you're getting is simply what you get when you sit down to type, without even thinking about it--then it's nothing to worry about, really. Pretty much everyone goes through at least one period where they end up with stuff that sounds pretentious and overblown; I did, multiple times (and could easily do so again/am doing so now!), and it's a very common thing for authors on these boards. As long as you don't get stuck there, you'll be just fine, and simply writing more, above all, will probably sort most of the problem out. You might also try reading some authors who write very lively prose
Other than that, Psychic's advice is absolute gold. There's nothing like reading your work aloud for finding problems with fluency. If you stumble in the middle of a sentence, you should try and find a way to rephrase it. In general, it's best to simplify, but don't feel like you have to always be slimming things down or think you're necessarily going in the right direction just because your word count is shrinking. Do try to look critically at each word in each sentence and think hard about whether it's really pulling its weight.
Reading aloud may also help you identify places where you're getting a little carried away with your prose--it might be a bit easier to assess "Would anybody actually say this?" or "Would anybody actually think like this?" when the words are actually coming out of your mouth. From what I recall you have issues getting flowery in characters' inner monologues and dialogues; there are some people who speak/think real "fancy", but generally speaking you should avoid that kind of thing.