it's been said that mario paint was the inspiration towards the upcoming mario level editor, but many popular youtubers got their hands on early builds of the game and found a hidden secret. upon designing a level you'll see a gray fly buzzing around, and upon hitting a couple more you'll get to play this little minigame. it would be nice as a full unlockable minigame, but unfortunately finding the gray flies upon designing a stage has been said to be a rare occurrence.