[Undertale]Did you clear the game?(Spoiler Alert)

Notes:(Spoiler Alert)People who have not done it yet, recommend that you do not read.

tobyfoxさんのツイート: "UNDERTALEをクリアした皆さんは、今から24時間後に、必ず @UndertaleJP をチェックしてください。 僕は、何か新しいものを作りたい。でも、それを始めるには、皆さんのフィードバックが必要です。 参加いただくには、パソコン（WinまたはMac）が必要です。…
https://t.co/EM5IkzxzRZ" https://twitter.com/tobyfox/status/1057256632000876544
██████(@UndertaleJP)さん | Twitter https://twitter.com/UndertaleJP

tobyfoxさんのツイート: "For those who completed UNDERTALE it's really important that you check @UNDERTALE 24 hours from now. I want to make something new, and it all begins with your feedback. A Windows PC / MacOSX PC is needed.… https://t.co/AeyvwQT9Xb" https://twitter.com/tobyfox/status/1057256452316901376
██████(@UnderTale) | Twitter https://twitter.com/UnderTale

The creator's "Tobyfox" seems to do something.
People who cleared the game once are eligible.

Well, what exactly is it?┐(´Θ`)┌

W. D. Gaster?