Very attractive! "Stacking" the characters like this does take some time.
HeroMachine does have the limitation of using one basic pose, at least in version 2 -- though it is, or will soon be (its still being a beta version), in small/medium/large, male and female. At least you can flip and re-size the result.
The free version 1 has two basic poses, "martial artist" and "superhero," though far fewer options to modify them.
Please do post your wallpaper in
the main HeroMachine thread over in the Bits section, as well.