As a concept, i think it's great. but I have to ask..why are you using a mouse and your opposite hand? Is this to challenge yourself?
As it stands now, the image seems kind of flat, especially in the foreground area.
I would suggest using more color in your concept, this will remove more guesswork or trial and error when doing the final image. Useing mid tones is a great way to start off, but there are so many colors, even in the mid range that can be used to help with the atmosphere and shapes.
I have the same problem of working with almost a mono tone pallet in the beginning and when I start adding more color things turn to crap. I'm NOT saying yours will, but for me that happens alot.