This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Mondo Medicals
On the surface, it seems like a simple anti-logical get-through-the-maze game. Then you get to the storyline. In the beginning you're told that you're helping research a cure for cancer. Wonderful, right? Well, not so much. After every maze you get what seems to be a transmission from some guy with a television for a head. You're not told who he is, but it's fairly obvious that he's supposed to be the fellow running the establishment. Every transmission gets a little bit creepier, with the only comic relief being the horrible grammar, but even that doesn't make it less scary; especially because the sound effect of the guy's "talking" is so insanely loud that it sounds like constant shouting. Then, when he starts going on about how "the cancer is death" and "To kill a cancer you have to shoot it"... you start getting the horrible feeling that something is just not right with this guy. Specifically in the area of sanity.
The whole game is set in a freakishly dark, totally black-and-white setting. There aren't many details in your surroundings, but that just makes it worse. A heavy breathing sound, presumably your own, loops through the entire game.
In the second level, you come across another TV-head-fellow. At first he appears to have a completely blank screen (unlike Crazy Transmissions Guy, who usually has a face on his). When you try to interact with him, a bloody, fanged mouth appears on its screen and there's a loud shouting-like noise. Try not to die of fright at this point.
The last level... It starts you out in an empty room. Nowhere to hide. Just the guy you've been talking to. Whereupon the guy yells, "I WILL CURE YOU, CANCER!" then a gunshot and you die. Nowhere to run, no way to escape it, no hidden way around. Just death.