The Green Demon Challenge is a Super Mario 64 challenge in which the mighty plumber has to collect a given stage's 8 red coin star while being chased by a 1-UP Mushroom. You must Collect all 8 coins and it's star without collecting the 1-UP; otherwise, you fail, and have to restart the stage to retry the challenge. The 1-UP is much faster than the average plumber, causing him to have to outmaneuver it in most situations. Hence, the name "Green Demon," as it's green, very fast, and can reach you from anywhere.
Vanilla Game VS ROM Hack Edit
In the vanilla game, Spawning the 1-UP requires you to climb to the top of a specific tree, and will give you an extra life if touched but without in-game consequences. In the Green Demon ROM Hack, however, the 1-UP will spawn at the start of every Level (or anywhere with an 8 red coin star for that matter), and will instantly kill you if touched. Also, the 1-UP becomes purple, for reasons unknown (although it may be in reference to the Poison Mushroom).
SimpleFlips's Playthrough Edit
Simpleflips began uploading the green demon challenge to YouTube starting February 6, 2018. Some stages got free passes, like Bob-omb Battlefield and Big Boo's Haunt, when the 1-UP got caught in a wall, or in Hazy Maze Cave, when the 1-UP got lost in the level.
Whomp's Fortress, Cool Cool Mountain, Jolly Roger Bay, and Bowser in the Dark World required about 6-10 minutes to clear, but with relative ease. Simple Second Tried (Basically First Tried) Lethal Lava Land, and First-Tried Shifting Sand Land and Snow Man's land.
Bowser in the Fire Sea Took great effort from Simple, and about 25 minutes of stream time to complete.
Dire Dire Docks is considered impossible, as the 1-UP spawns very quickly, and Mario immediately lands in water, which slows the plumber down.
Currently, Simple is in the process of completing the 8 red coin challenges in the ROM Hack Super Mario Star Road