We factory sim perverts have all known the joy of combing a mile of conveyor belt tagliatelle for that one empty hopper or unplugged furnace that’s stalled the entire production line. Now, imagine that the stalled production line is producing plasma swords for your army of murder droids.
You need your army of murder droids to fight another army of murder droids, but unfortunately, all of your murder droids are now swordless, and therefore murder droids no longer. They advance placidly into the firestorm, falling like mown dandelions, while you run your cursor desperately over the hexagonal smokestacks. There it is! A misfiring 3D printer, right in the centre.