- Sonic the Hedgehog 2 contains data for a cut level called “Genocide City”
- Obscure Wolfenstein clone Corridor 7 randomly jumpscares the player with a red demon face during regular gameplay
- Dog Island, a Wii game in which all the characters are adorable chibi dogs, has a subplot about a doctor whose botched treatment caused the death of someone he loved many years ago. He still sees her in his dreams, unable to let go or move on.
In dungeon keeper there’s a hidden message from a developer about how working on the game has taken a toll on their health and social lives; there’s another game with a far more haunting hidden developer message but for the life of me I can’t remember the game.
In (thief 2?) there’s a ship with a corpse in it; the corpse is seemingly alive as it bleeds when you attack it; it almost can’t be killed, but if you carry it to the ship’s edge and dump it overboard, you hear it die. It’s most likely supposed to be a vampire, probably inspired by Dracula as Dracula in the novel also traveled at one point via boat (wherein he killed the crew).
Here’s the Dungeon Keeper message, courtesy of The Cutting Room Floor:
spoiler