for me the reason it looks like a game is cause your textures look like they are too low res and there's no shadowing pretty much anywhere... (trademarks of games! ) did you use real photographs for your textures? if not then you're going to struggle to make it look real. You also need to be lighting your scene to match something. There's no point in doing it without a background image e.g. your sky or a bg plate or whatever.. it'll never look real.
Alan
Technical Director - Framestore
Currently working on: Your Highness
IMDB