All wallpapers made with the current version of Gimp.
Making video game art is something I have always wanted to do, I just lacked the skills to do it electronically. In January of 2014, I was stuck in the house for 2 days due to a snowstorm. I made myself learn how to use Gimp by trial and error. It's not that hard, but the software could use some improvements to make it more intuitive for beginners.
I approach each wallpaper as if it were a piece of art I would want displayed on my computer. First I create one piece that is pretty much true to the original game. Then I put that on my computer and let myself stare at it for a day.
Then I ask myself what could make this game even better? More villains? More bullets? More levels?
Then I go into the image and double up on everything until it looks crazy over the top.