All hints and locations necessary for accessing the multiplatform easter egg without having to dig through random forum threads, Youtube videos, or anything else.
Guide to Accessing the Multiplatform Easter Egg
Version 1.3 marked the release of CrossCode on Switch, Xbox One, and PS4. The release also included a new, exclusive side quest and pet for each platform. At the end of the dungeon portion of this quest is an optional display with a message from "The 4 Visionaries". To access the easter egg, this display must be accessed to provide the key item necessary to progress the easter egg, as well as a platform-specific clue. The intent is to hunt down all four clues from each of the four platforms (such as by reading this guide!) and use them to visit the four indicated locations to unlock the fifth and final location.
It should be noted that there are no rewards for completing this easter egg. If you're just in it for in-game rewards, you can skip this entire task. Also, this guide will not cover the side quests for any platform; this is just for the post-quest easter egg.
Autumn's Fall, "North of a big ruin, surrounded by water".
Xbox One Clue
Bergen Trail, "Between a laser bridge and the hidden lair of Frobbits out of reach".
Maroon Valley, "At a hidden source of water, uncovered while searching for cursed treasure.
Gaia's Garden, "At a crossing, on top of one of the four tree stumps".
Easter Egg Location
All four clue locations must be visited with the key item from the quest!
Once the four hints have been visited, entering the final location will trigger a tracker to point you to the elevator.