I think we need a bit of background to crit this effectively. You say it's almost finished, but don't give us any idea of what it is or what it does, how it moves etc.
I love your painting style. Everthing looks chunky and yet detailed. I think you need to plan your ultimate destination when you start the piece. As has been mentioned, propulsion and location are unknown factors which would have an impact on the piece. Again detail would be important, and a splash of colour would be nice. If it's organic, look at exotic insects, if technological, use industrial machinery or aerospace stuff as references.
Death is always on the way, but the fact that you don't know when it will arrive seems to take away from the finiteness of life. It is that terrible precision that we hate so much. But because we don't know, we get to think of life as an inexhaustible well. Yet everything happens only a certain number of times, and a very small number really. How many more times will you remember as certain afternoon of your childhood, some afternoon that's so deeply a part of your being that you can't even conceive of your life without it? Perhaps 4 and 5 times more. Perhaps not even. How many more times will you watch the full moon rise? Perhaps 20. And yet it all seems limitless.
-- Paul Bowles
The Sheltering Sky