This goes to Geometry Dash without a doubt in my mind if you include user-created levels, and I do as long as they’re officially rated with stars, especially if they’re e.g. in a Gauntlet (which a number of Easy and Medium Demons are).
If you allow in star-rated levels outside of Gauntlets, then I think it’s safe to say that Tidal Wave on its own crushes the difficulty of basically any video game ever made that’s ever been completed by a human. GD is an interesting case where you can make it as easy or as difficult as you want because there’s no true “ending” to the game (getting to the Demon Gauntlet is part of an actual storyline, but when you beat it, it goes nowhere, so that’s weird).
if you include games with user-created levels there’s quite a few games with levels that are practically impossible for a human, eg. trackmania and super mario world
As noted, “that’s ever been completed by a human”. Otherwise there’s simply no ceiling; I can just create a game that requires you to perform 10 frame-perfect inputs every frame for five months straight and say “now I have the hardest game since it’s technically possible to win; checkmate.” With user-made levels, there’s still a ceiling defined by a human actually completing it, and I don’t think the human-beaten Mario Maker or Trackmania levels touch the extreme levels of difficulty at the highest skill levels of GD.
TL;DR: I think if we include user-made levels ever beaten unassisted by at least one human, Geometry Dash wins.
I’m pretty sure the trials of death in super mario maker wins.
Over 4000 hours over 7 years just to beat one level.
