Hi again,
I’m sorry I think I came in too strong. Theres nothing wrong if you post your work here. What I meant was you might not get a very good feedback thats all. Since most people who post their work here major in realistic (or semi-realistic) background images aka Mattepaintings.
Like I said its a very good piece of artwork… and I like what you did here.
As for category, well if I were to categorize it, it would be more under digital painting and/or photomanipulation. I’m not really into specifics since it gets quite messy.
Mattepainting is more on realistic background images, well most of the time that is. Basically in VFX mattepainting is used to :
- Extend a background (e.g. Indiana jones, Cloverfield)
- Create a realistic (photoreal) background (e.g. Star Wars, LOTR)
You can however create one artwork that is related to this, like maybe make the background of your artwork more realistic and lessen the painterlly look and the fx. That would fit in.
Like I said there is no strict rule, just a little reminder that may help you in the long term.
Hope this clarifies everything. 
Have a great one mate.