I was thinking of going to do more of the mountain, but I was lazy at the time and felt clouds would be the perfect cover. Plus, it made the tower contrast more with the sky.
The only thing I can reference here is that the robot's stance is an homage to Starman from the Mother games.
There was a bit of experimentation on this one. I wanted to try a techinque Mike Krahulik used on a piece he did of Gears of War. He did a beautiful job with sunlight reflecting off the back of a character. I don't think I did it exactly the way he did it, but it's close. The clouds were done just by painting white splotches, then using the smudge tool to push it around.