I decided to call the stripy lizards
Rommelards, if anyone's interested.
Here's another picture of a Dune Cat, this time coloured entirely in GIMP.
I traced the outline of an existing picture by hand and scanned it in, then coloured it in on the computer. It took me around an hour and fifteen minutes; the same amount of time it would have taken me with oil pastels by hand.
What I like about GIMP is that I can use it in the same way as I use my oil pastels; I use a thick paintbrush to whack down slabs of colour, then I use the Smudge tool to blend it with the surrounding colours and the background colour. If I want to blend it still further, I use the Blur tool to haze the outlines even more.
When I use oil pastels; I do much the same thing; I scribble a layer of oily wax down, then rub it in with a finger until it's smoothly blended in.
When I'm oil pastelling, I also often shade in large areas with coloured pencils so as to save wax; proper oil pastels are expensive. With GIMP, I use the fill tool first to colour in all the areas, then add the blendy and airbrushy effects.