I had a dream two nights ago that basically played out like a movie.

The plot was about a race of aliens who, fed up with the way humanity had despoiled the planet, altered the sun into a dim green star which had begun to emit mutagenic radiation which was turning everyone on the planet into homicidal lunatics. Once everyone had slaughtered each other in a great orgy of blood, the radiation of the green sun then would act as an evolutionary accelerant to help produce a new sentient species to act as humanity's successors.

George C. Scott was in a starring role with Brad Dourif supporting.