Semispheres original icon is so vague and ugly, I'd have to say that one.Which icon would you guys say is the absolute worst? That includes icons which have since been replaced.
I might have to lend my vote to Steamworld Dig 2 on that one. Hoo boy.
Mr Shifty's original was also pretty terrible. Not only is it a lame icon, but it was also low res, so it looked like garbage.