Sleep Bug was a game that was used by Syntax.
After realizing that one of the six items that would create the bone mech was at the Cloud, Syntax created Sleep Bug to make the Guardians of Knowledge and the people of Megapolis fall asleep. Once MK learned the truth of the game, he head toward the Cloud to get rid of it. After confronting the Game Monster, MK used a book to destroy it, waking up everyone who played the game.
The Game Monster was the living embodiment of Sleep Bug. After MK learned that the game was making everyone fall asleep, MK confronted the Game Monster to destroy it.
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