The Portal series. Easily two of my favorite PC games, and mind-blowing when you really think about them. Maybe even a little creepy.
For example, what happens when our heroine Chell gets caught between two portals?
Infinity happens, and it’s a bit unsettling.
“People with apeirophobia really shouldn’t watch this. Everything has been recorded at first-person perspective. It resulted in infinite psychedelic visuals such as giant spirals, never-ending walls, and gigantic perpetual portal rooms. Scary at first when you’re face to face with yourself. Such visuals potentially can trigger anxiety about mirrors and stairs to some people…Chell doesn’t die by doing this, and it looks like there’s no gravity anymore.” – CrowbCat