Mettaton NEO is a form of Mettaton specifically designed for human eradication. He appears in Undertale as a boss fight. It is, according to the game's description, Dr. Alphys' "greatest invention." This form of Mettaton only appears in the Genocide Route. In battle, Mettaton NEO does not attack or do anything, likely because this form was intended to be killed in one hit during the game's creation. Mettaton NEO easily dies in 1 hit, presumably due to the strength of the player at the time of the battle.