My vote goes for Tomb Raider II and the floating islands levels. The game is a relativity normal globe trotting affair for Lara until she gets transported into the fucking shadow realm here. This level gave me major scares as a kid since you're traversing a giant void being chased by animated statue warriors out to kill you.
On both versions of Shrek 1 you can get out of bounds on most levels and fall into a void. On the Xbox version you fall into a sort of chicken purgatory that you could only exit by turning off your console. During the credits there is artwork of the main bad guy flying with chickens and there is also a cheat about him that may or may not do anything. This has kept me up at night for two decades.
here is footage of the chicken room
Well now we are all cursed so thanks