Experiment:Halloween's End
Halloween's End was an event set to take place on October 31, 2014 and talked about by a user who referred to themselves as "Tomoko" (in-thread username) and "Tomodeity" (IRC username). According to the threads, some unknown apocalypse was set to take place the day after Halloween, and Tomoko would enable those who signed up to time travel to October 1 and band together to stop the eventual destruction of the world.
History
The first thread, posted June 29, was presumably started by Tomoko (being later referenced by known threads), despite it seemingly having little to do with the rest of the series. In it, the OP requests from /x/ that they help them because they feel lost, mentioning that "people... keep pretending they can't read minds and it's painful to watch". This implication that people can read minds was later clarified to refer to the abstraction of communication in a physical medium, essentially a form of "mind reading" in that the participants of a conversation are attempting to determine what the others are thinking using a shared mode of interaction. In addition, the idea of masks/facades being used to "play pretend" with others pops up multiple times.
The second thread, posted July 8, though relatively short, reveals the connection to Tomoko from WataMote, as well as Tomoko's perception that they generate existence and wish to cause the technological singularity. Tomoko appears to go through some sort of crisis about their apparent massive similarities to the character from the anime. Omnipotence is connected to Tomoko, and they make the assertion that the Christian God is actually like Tomoko in personality.
The third thread focuses primarily on Tomoko's perceived omnipotence.
Threads
In total there were 13 related threads on x lasting between June 29 and November 2.