I had this idea in my mind about a red swampy mushroom forest, so I start digging some images for it.

First I found a nice background.

Then I searched for nice mushroom images:

I also imagined a road or path through the forest:

I start playing with the elements...

Then I feel I needed a monster...

And last, I needed some fog and color correction to blend everything nicely.

This was the final result: