Once G was shattered across time and space from an overload of DT after jumping in the Core, that DT caused the pieces of G to briefly gain a modicum of control over every part of Paratale he was in, causing the timeline to split from the initial hundred or so caused by Flowey's resets, to thousands.
Initially, G had a theory for what caused these timeline splits, and assigned them "Functional Universe Number" values for every universe, and detailed how they were different. His first theory for which he assigned these is outdated, but the current theory, that is correct, is:
When someone with DT interacts with a timeline, the timeline splits to another for every reset performed, or every timeline interacted with. G's overload of DT caused several new timelines to be made that are nearly identical because they all split off of one timeline, FUN value 66. But every other timeline was corrupted by his sudden absence, and some things went wrong as it tried to course-correct, creating copies of people he knew while trying to search for him. Sometimes he found parts of him could speak through these people, sometimes they couldn't. They all seemed to be aware of him despite his state, though.
But then, as PLAYER_ entered the world, there seemed to be a PLAYER_ for every one of these timelines, practically doubling the amount of them. But that would only be the case if every PLAYER_ was technically a different entity, like his scattered parts... And then, the FUN count started to get out of hand. The number of universes went from thousands, to hundreds of thousands, to millions- G could no longer keep track of them, as the scattered parts of himself couldn't even approach the number of PLAYER_s wreaking havoc.
At this point, G recognized the lack of power he had had diminished to even less, and decided to focus his attention elsewhere, as much as he could, of course. His scattered parts created a hivemind of sorts that was hard to keep track of. This caused G to run into the code of the "game" he was in, and by extension, some part of the wider multiverse...
There is a PLAYER_ for every actual playthrough of Undertale irl even if the details in Paratale don't line up exactly with canon, Paratale is legitimately a self-contained multiverse of itself in this way. If it inspires you to make your own PLAYER_ sona/oc, go ahead lol.
The different fun events are caused by the PLAYER_ starting from different various Flowey Reset timelines, where different things he did caused differences between playthroughs. And Fun values are actually the names of each timeline.
areudirty
kaledo-art
vaporwave
yousharknotpass