An Alternate Reality Game created by the Reddit user beansinjeans2019, World of Theseus is a Massive Multiplayer Crossover primarily focused around Deltarune. Strange things are happening in Hometown, with residents mysteriously going missing... or not. Everything is going just as it ever was.
World of Theseus contains the following tropes:
- Art Shift: Linc's talksprite uses a much higher pixel resolution than other characters and has a border around it, to represent the fact that they came from a different world.
- Bathos: The Outsider, the first Arc Villain of the series' talksprite... is a distorted png of Thomas the Tank Engine.
- Benevolent A.I.: Random image generating AI, of all things, is capable of recovering images of people that have been recycled.
- Big Bad: Wild Card, the creator of the Outsiders.
- Demonic Possession: An Outsider possesses Lori to lure Kris in.
- Different States of America: The series is set in the USDA: The United States and Departments of Amerigia
- Eldritch Abomination: Outsiders are diamond-shaped beings described as "ungraspable" that are capable of possessing and recycling beings.
- Entry Point: The first clue is a Reddit post on beansinjeans2019's account.
- Lotus-Eater Machine: Berdly is trapped in one after being recycled, with an implication that Asriel is in one too.
- Massive Multiplayer Crossover: Although the series primarily focuses on Deltarune, it also contains signficant cameos from other series such as The Loud House, Steven Universe, Thomas & Friends and Sonic Underground.
- Ripple-Effect-Proof Memory: Berdly has the ability to remember the existence of people who were recycled due to coming in contact with The Soul.
- Stellar Name: Zig-Zagged: Inverted out-of-universe, with various planets in the world's solar system being named after certain characters, such as the planet Chara and its moon Asriel. Played straight in-universe, with those characters being named after the planets.
- Unperson: The fate of anybody who is "recycled", with them being erased from the memories of everybody but Berdly. At least, until Berdly himself got recycled too.
- Whole-Plot Reference: Characters being replaced by copies that are unnervingly similar yet unnervingly different? The Intruder and The Outsider even have similar names!