PlaymateA small child wanders on a desolate beach, wearing a WWII-esque Mickey Mouse gas mask ([link]). The water has an oily green tinge to it. And empty can lays nearby, with a faded toxic waste symbol on it. He's singing quietly to himself: "I've been working on the railroad, all the livelong day..."
He starts to build a small sand castle, still singing to himself. A strange breathing slowly fades in, along with footsteps, as the boy continues to build the sandcastle. The tension builds up.
Finally, there are a pair of feet in the boy's view. The skin is strange looking, rough and scarred. The boy looks up. Another child, mutated from the toxic dump, stares down at him, his breaths hissing. His face is elongated, echoing the boy's gas mask. The two stare at each other for a few seconds.
The mutant then bends down and starts helping the boy build the sandcastle. They work on it together.