I really don't think you should fall into the trap of over-working this, you've emulated the atmpsphere beautifully.
My only niggle would be the sharp absense of green directly behind the foreground dropping straight into a primarily purpley/blue background, it seems slightly detatched to me. I think there should be more of a transition but I understand for the purpose of a game the distinction is needed.
Good work, I really commend the patience.