I Have No Mouth, and I Must Scream, Harlan Ellison's post-apocalyptic short story, was quite affecting to a young me. While many cite 2001: A Space Odyssey's HAL or Terminator's Skynet as the greatest AI villain, for me it will always be AM, I Have No Mouth's impossibly cruel supercomputer.
AM's been keeping the last five humans on the planet alive for 109 years, torturing them endlessly. It's a horrific tale that deals with all sorts of moral quandaries, covering topics like the Cold War, rape, and genocide. The adventure game of the same name, developed over 30 years after the short story, covers the same topics, with a bleak art style and some bloody tough puzzles.
It's an unpleasant experience, with incredibly flawed characters and an oppressive feeling of despair permeating throughout the entire adventure. So you should definitely play it, then. The good news is that it has appeared on GOG.com today and can be yours for a measly $5.99. You can thank me for ruining your weekend with bleak sci-fi horror later.