An alternate timeline of Inverted Fate. MarioTime stops Flowey before his plan. He k!lls Flowey, erases Flowey's memories, and resets the timeline to how it was before, keeping what he liked from Inverted Fate. Essentially, all of the characters remember what happened in Inverted Fate, minus Flowey. They don't remember Flowey, however. But other than Frisk still talking, it's exactly like Undertale.
