The Mount Chiliad Mystery
The most elaborate Easter egg in GTA 5 is the Mount Chiliad Mystery — a series of cryptic mural symbols, mysterious hatches, and scattered map clues that suggest a massive hidden conspiracy. Years of community investigation eventually uncovered UFO encounters, jet pack locations, and supernatural events — but the mystery was intentionally designed to resist complete resolution.
The Ghost of Mount Gordo
Between 11pm and midnight in-game, a ghostly apparition appears at the cliff face near Mount Gordo. The ghost resembles Jolene Cranley-Evans, murdered by her husband Jock Cranley. An in-game website confirms the murder mystery's details. This is one of GTA 5's most haunting and atmospheric hidden secrets.
The Infinity Killer
A series of wall etchings across the map, combined with 8 bodies hidden in specific locations and a series of cryptic number patterns, reveal the story of the 'Infinity Killer' — a fictional serial murderer with a fixation on the number 8. Following the trail to its conclusion reveals a note explaining the killer's methodology.
UFOs and Aliens
Multiple UFOs appear across the map under specific conditions: a submerged UFO at Fort Zancudo, a holographic UFO above Mount Chiliad (only at 100% completion in rain at 3am), and a crashed UFO near Sandy Shores. An alien frozen in ice lies at the ocean floor near a spacecraft wreck site.
The Epsilon Program
The Epsilon Program — GTA's cult parody — is a fully playable side mission chain involving Michael. The missions involve bizarre rituals, large cash payments, and ultimately a choice that determines whether Michael profits or loses everything. The Epsilon storyline is one of the most satirical extended sequences in the game.