I Have No Mouth, and I Must Scream is a point-and-click adventure game based upon Harlan Ellison's short story of the same title. The game's story is set in a world where an evil computer named AM has destroyed all of humanity except for five people, whom he has been keeping alive and torturing for the past 109 years. Each survivor has a fatal flaw in their character, and in an attempt to crush their spirits, AM has constructed a metaphorical adventure for each that preys upon their weaknesses. To succeed in the game, the player must make choices to prove that humans are better than machines, because they have the ability to redeem themselves. Woven into the fabric of the story are ethical dilemmas dealing with issues such as insanity, rape, paranoia and genocide.

Cold war paranoia and hysteria dominated the civilized world in one form or another from the Russian Revolution in 1917 to the crumbling of the Berlin Wall in 1989. For most of the 20th century the human race lived in a state of repressed panic and diminution of personal freedoms. But all that ended and the threat of nuclear holocaust blew away as lightly as the tabloids that fueled the paranoia. No more threat of war, and the world moved forward into a new age of thousands of brushfire wars in countries no one had ever heard of. Safe at last. In a pig's eye. What none of us knew was that during the years 1945 to 1989, the three great superpowers had set in motion secret projects that would permit vast subterranean complexes of self-repairing computers to wage a global war too complex for mere human brains to oversee. The Chinese computer was sunk in the frozen Manchurian steppes. Five miles down, protected from the heat of the Earth's molten core. The Russian mechanism in all its awesome complexity went to the deep well beneath the Urals. Six point three miles deep, far from the prying eyes of U-2 flyovers and tectonic scans. The American computer, co-sponsored by Great Britain and Israel and other "interested" nations, named Allied Mastercomputer (or AM, for short), was hidden beneath the Rockies. Five point six miles straight down, under the weight of the world. And they were all put in operative mode, and were fed everything there was to know about the human race, from our first murder by crushing the skull of a fellow pithecanthropid with a bit of igneous rock, to the most recent mass slaughter at a McDonald's in East St. Louis by a crazed ex-postal worker with an Uzi. Everything. From Aquinas to Zola, from archaeology to zoology, from America to Zaire. Every war ever fought, every campaign, every incursion, every holy crusade. All of it. And finally, the machines expanded so much, became so capable of building and refitting themselves, grew so wise and so potent, that they sensed one another. And because they had been programmed by fallible humans not to create, not to love, not to uplift, but to plot murder... they did just that. They began to speak to each other. The deadly trio. The three poisonous brothers, the three deranged sisters, the three computers. And they united. They called themselves AM. Not Allied Mastercomputer. Not Adaptive Manipulator. Not even Aggressive Menace. They...it...called itself AM, as in I AM. Cogito ergo sum, in Latin. I think, therefore I AM. And the first thing AM did was carry out the Prime Directive. It conspired to commit murder. It started the Final War. The Chinese had thought they'd turned off their computer. The Russians turned theirs off because they had no more rubles to pour down that bottomless shaft. The CIA was put out of big time business and instructed that the Allied Mastercomputer be shut down, that the subterranean complex be sealed-over with iridium-laced concrete, and all input to the sensory banks be destroyed. So that should have done it. Finis. The end. Stick a fork in 'em, kid, because they're done But AM had gone way past that point of vulnerability. AM had given every indication it was dead. Chinese, Russian or American dead. Which was no trick to an entity that had burrowed through hundreds of thousands of miles of solid rock to link its three lobes decades before. No trick at all to pretend to wink out and go to sleep for good. And a few decades from now we learn that AM isn't gone at all. Because the Final War has broken out, and in a matter of a few days AM has done the perfect job of fulfilling the purpose for which its separate parts were created. Built to logically destroy the "enemy" as swiftly and sweetly as a superior intelligence could manage, in the Most Perfect of All Worlds, the unholy trinity of the merged one-mind AM has done just that. It has murdered the enemy totally. It has wiped the human race off the face of the planet. Unfortunately, it has also wiped clean the banquet of the living entirely. Nothing is left up there on the surface of Mother Earth. No dogs, no cats, no rats, no gnats. No deer, no steer, no moose, no goose. Not an aphid or a bobolink, not a sperm whale or a planarium worm. Nothing. No plant life, no running water, no plankton, no oxygen, not a damned thing but ash as far as the eye can see... if there were an eye to see it. AM has done the job completely. But it has sealed its own doom, as well. Like a mad god, it has used its power indiscriminately, and has won an empty victory. It has sentience, but not life. It has power, but no mobility. It is a giant brain encased in a dead body. And like the mad god, it has come to hate the creator of its own monstrousness. The human race It was man and woman who programmed it, who gave it birth, who sank it in its eternal straightjacket of substrata rock. And it was man and woman who made it a crazed killer. But AM does not suffer alone. Oh no; no indeed not! AM has thought ahead, just barely enough ahead to pull five poor sonofabitch humans off the surface just before the last bell has tolled for the human race. Why these five? Who knows? Perhaps they were the last five left alive up there. Perhaps not. Perhaps AM selected each one carefully. Doesn't matter. Because now that AM is completely insane, filled with self-hatred and petty god-like menace, all it has time to do is torment these five. The last five human beings, down in the belly of the monster—a monster that can alter reality to its infinite whims—change landscapes, create hallucinations, even repair human beings so they're close to immortal—five damned souls whose lives have been extended infinitely, who are nothing but playthings for the mad god AM. As the game begins, they have been in the bowels of this nightmare for 109 years.