First, a necessary confession: “Quackprep” is not an official term, character, or location within Undertale. It does not appear in the game’s code, nor in any official merchandise. Instead, “Quackprep” is a folkloric internet handle—most likely the username of a now-obscure content creator from the mid-to-late 2010s.
Based on archived forum posts (from Reddit’s r/Undertale, deleted Tumblr threads, and YouTube comments), a user named Quackprep or QuackPrep was active in the Undertale fan community around 2016–2018. Their claim to fame was a series of unedited, “full” game playthroughs, often with specific constraints: no commentary, no deaths, “true pacifist” runs, or, conversely, “genocide speedruns” with developer commentary disabled.
However, the phrase “Quackprep Undertale Full” gained a secondary, more mythical meaning. Quackprep was rumored to have uploaded a complete, uncut, 6+ hour video of Undertale that contained anomalous glitches—things that shouldn’t exist in the base game. Viewers claimed to see:
These claims were never substantiated. Most likely, the original Quackprep videos were simple, clean playthroughs. But the internet, ever hungry for creepypasta, transformed them into a vessel for Undertale’s most potent narrative: the idea that the game is haunted by its own cut content. quackprep undertale full
Why “Quack”? Why not “SeriousPrep” or “GasterRun”? The absurdity is crucial.
Undertale’s fandom has long embraced nonsensical humor as a coping mechanism for its emotional gut-punches. Consider:
“Quack” evokes the same energy. It’s silly. It’s duck-like. It shouldn’t be associated with a harrowing, 6-hour genocide run. That juxtaposition—childish sound + obsessive archival behavior—is pure Undertale. The game itself teaches you that cute things (Flowey, the temmies) can be monstrous, and monstrous things (Sans, Asgore) can be deeply sad. First, a necessary confession: “Quackprep” is not an
Quackprep, therefore, is the perfect avatar for a fan-constructed creepypasta: a goofy name for a terrifying archive.
If QuackPrep originally streamed Undertale on Twitch before exporting to YouTube, the highest quality "full" files may still exist on their Twitch "Past Broadcasts" page. However, Twitch deletes VODs after 60 days for non-partners, so most have been migrated. Check the "Videos" > "All Videos" > "Past Broadcasts" section.
Unlike traditional RPGs where you grind for experience points (XP) and kill everything in your path, Undertale presents you with a radical choice from the very first encounter: You don't have to kill anyone. These claims were never substantiated
The game operates on a unique morality system that tracks your choices not just in the current save file, but sometimes in the game's hidden files (the "save folder"). This means consequences are permanent, creating a sense of weight to every action.
To fully understand Undertale, you must understand that there are three distinct narrative paths. Your experience changes drastically depending on how you play.
If you manage to locate a “full” QuackPrep compilation, expect:
For the uninitiated, "Quackprep" refers to the YouTuber and streamer known for a very specific brand of humor: high-energy, voice-acted madness, and a dedication to the "bit" that borders on method acting.
Unlike traditional playthroughs that treat Undertale with hushed reverence or focus purely on the emotional weight of the story, the Quackprep approach is a variety show. It turns Toby Fox’s indie masterpiece into a chaotic stage where every NPC gets a new voice, every battle is a comedy sketch, and the fourth wall is broken repeatedly.