ok now ive deleted that garbage here is the real thing.
the neutral route occurs if one of these are true:
the player has not completed a genocide or pacifist before
the player has not befriended Sans, Alphys, and Undyne
the player has killed one, but not all monsters.
the boss of this route is Photoshop/Omega Temmie.
this is always the first route you accomplish without a game editor.
in this route temmie absorbs all 6 human souls and becomes omega/photoshop temmie, making a save file titled Temmietale.