I’m only counting single-player experiences created by humans; which are possible to beat.
In 2017, speedrunner and live-streamer The Mexican Runner set out to beat all 714 official NES titles in his “NES Mania” challenge. The NES was one of the most limited home consoles, sourcing from a time when home gaming was just starting to become a thing, and it took this man almost three years to finish the series. Now consider the SNES’ library with over 1000 more games. The N64. All the PlayStation consoles; the XBox games; and of course the ever-thriving PC indie game scene. The NES 40KB size constraint is a relic of the past. Some video games have 100 hours of content. Some games have stupidly long grinds that take hours.
The biggest obstacle would not even be the really challenging games; or those with really long grinds. It would be the shear volume of content. Most would spend far longer on short games that you can complete in a few attempts, than on anything that would be a severe challenge to the average “gamer”.
Yes I am familiar with Desert Bus. I was thinking of that game and a few based off it when I wrote my second paragraph. That, and the abundance of flash games targeted toward kids.
For “possible to beat” I really mean possible. Not humanly reasonable. If there is a way for a standard human to do it, as difficult as it may be, it counts. Unless the game is unfinished, has no means of completion (like some Action52 games) or is impossible by design—like, the player can not cross a gap impossible—it counts. For stuff that requires staying awake for 100 hours… I suppose stimulants could be provided. That or you switch to polyphasic sleep.