Homestuck
Homestuck is a webcomic in Repitonian culture and the main inspiration for Vast Error in real life.
As a Webcomic
Homestuck's main premise is that of a group of human friends playing a hyperreal sandbox/adventure game that causes the apocalypse of their home planet, Earth, and their own transportation into an alternate dimension known as The Medium as a means to play the game. They learn of their destined roles as holders of aspects of reality, with their ultimate aim being to create a new universe to inhabit using the means the game provides.
Throughout their quests, they are contacted by a group of internet trolls who are eventually revealed to be members of an actual alien species known as trolls. These twelve particular trolls are the last of their kind, having played their own session of the same game but being unable to finish due to circumstances retroactively brought about by the humans' session — the humans' own universe being the universe created by the trolls' session, one that was doomed from the start by forces greater than any of them could ever know.
The humans and the trolls then work together to salvage the remains of their respective sessions and use a game-provided means to reset the humans' universe in hopes of being able to finish the game in the new session and continue the cycle of existence. In the process, the humans rise to very high states of power over their aspects, each by inadvertently ascending to the god tiers, the highest levels one can achieve. Only one of the trolls had reached this state in their session, and one other also achieves this state after their session.
As the trolls assist the humans, rising tensions among their own party as well as the violent tendencies they had all been groomed into by their society result in the deaths of about half of the group. The remaining trolls meet one half of the human party, the other half having taken a different route to the new session.
After a three-year gap spent traversing the incomprehensible void between the collapsing human session, the now-desolate troll session, and the new post-reset human session, all surviving members of both sessions rendezvous at the new session, where all hell breaks loose. Due to the convening of multiple antagonistic forces and the unpreparedness of the players to deal with it, all having been sowed by the highest antagonist of all, the session meets a calamitous end.
At this point, the first and main character of the comic, having inadvertently gained an unrestricted amount of power over the entire narrative of the story, retcons a select few moments of the past to ensure that the disaster that struck and all things that led up to it never come to pass. These actions turn the final conflict heavily into their favor, and the players manage to survive the battle and finally step into their new universe.
As an Inspiration
Vast Error as a story stems very directly from Homestuck in many of its facets; trolls as a species and all concepts surrounding their biology and culture, classes and aspects and the very concept of The Game, the carapacians and their moons, and the comic's format and art style as a whole are all derived from this work, to name a few. Subsequently, the main cast are all written to be deconstructions of common archetypes found in original troll characters created by fans of Homestuck, and this deconstruction of tropes on a metanarrative level, especially tropes instated by Homestuck itself, is one of Vast Error's core themes.
In Vast Error
Multiple references to Homestuck crop up in Vast Error, to the point that it's undeniable to state that the work exists physically in-universe. Whether the Homestuck that exists in Repitonian culture is different to the webcomic of real life is unknown.
On top of the above-pictured vinyl figure of the comic's main character John Egbert found in Arcjec's hive, multiple direct references to the comic are made on several levels ranging from a cheeky line spoken by Cadlys Rankor in his route of Snowbound Blood to the Dead Shufflers actually encountering and interacting with their Homestuck counterparts in Intermission 2 Side 1.
When Calder examines a portrait of a human, he implies that humans are part of "what's going on in webcomic culture". This may mean that on Repiton, humans are a fictional species created by Homestuck.