This movie is really disturbing, and many people (myself included) have been caught off-guard by it. It was brought to my attention again because the director is in charge of the film adaptation for Castlevania.
I love horror movies even though I tend to be very critical of them. However, this is now. When I was a kid, I spent 6 months on light medication after being scared to death by trailers for several movies like Alien, Phantasm and The Fog, which were released about the same time. Although it was not quite life-threatening, it’s not an experience I wish any kid to go through.
Event Horizon evoked some of that terror, and I remember spending the couple days feeling nervous and in a state of general unrest. Quite an accomplishment I would say, and I’m still unsure exactly WHAT kind of devices this movie uses to achieve such effect.