This is a cover I did for Paradox interactive's Naval War - Arctic Circle game a few years ago.  This particular cover was on a very tight schedule and a very tight budget but I was given a lot of creative freedom by Paradox from the very start and was responsible for the image from concept to final execution and retouch.  I started,as usual, with ingame (in this case very low res) models and built up detail by modeling and also encorporating purchased stock models.   Background was a mixture of digital painting and photomantaging. Below is how it looked on the box with titles.  

Some closeups at about 50% resolution.  Final size for this piece was 5000x7000 pixels.