"Another Eden: The Cat Beyond Time and Space" is a Japanese role-playing game developed by Wright Flyer Studios and published by GREE Inc. for iOS and Android devices. The game was released in Japan in 2017 and later worldwide in 2018. It features a time-traveling narrative where the player, accompanied by a cast of characters, must travel through different eras to prevent the world from being destroyed.
The "Millennium's Worth of Memories" or "Millennium's Worth of Dreams" (千年のメモリーズ) is a term used within the game, but it's not specifically referred to as the "Millennium's Worth of Dreams" box. The game does have a concept of "Dreams" and "Dream Keys," which are items used to unlock certain events or areas within the game. However, the term "Millennium's Worth of Dreams" is not a direct translation or a well-known term associated with the game's lore or mechanics.
It's possible that the phrase "Millennium's Worth of Dreams" is a fan-created or localized term that is not officially recognized by the game's developers. The game's story is rich and involves multiple dimensions, time travel, and the exploration of different eras, so it's understandable that players might come up with their interpretations or nicknames for certain aspects of the game.
If you're referring to a specific in-game item, event, or story element, it's best to consult the official game materials or the game's community for accurate information.