Once I found a YT video called "The History of World 4-2" (
Super Mario Bros. level). I thought oh, maybe it's a perspective on game design using the evolution of a single level as an illustration of level design principles.
Nope -- it was speedrunshit. Basically, Guy A found a glitch that let him shave fractions of a second off, and then guy B found another glitch that let him shave a few more fractions of a second off, et weary cetera. The big deal about World 4-2 is that in Super Mario Bros., where you go when you go down a pipe or climb a vine is selected by the x-coordinate of the screen scroll position, so if there were a way to run past the vine that leads to the 6-7-8 warp zone and go down the pipe immediately following without scrolling the screen to the right far enough to change the pipe destination to the coin room, Mario will go to the warp zone area instead without the time-consuming vine animation, saving a few seconds. But this is only achievable by jumping backwards in a few frame-perfect jumps throughout the level leading up to that pipe, which in turn must be speed-optimized to shave a few milliseconds off so you can beat the other guy's Any% world record and... arrrrrgh. That's what World 4-2 was to these people. Not a little segment of a fantasy world. Not even a beautiful artifact of human art and design and how it communicates with the player, the messages the design itself shares with the person operating the game. Just a set of glitches and hacks to exploit to get through the game faster, and the history of the level was the history of finding these glitches to decrease the world-record time. How basic is it that I can remember discovering the 4-2 vine and my mind was blown at the revelation of this little secret!
Just today I saw another germane YouTube video called "Dear Developers, Stop Listening to Pros", ( https://www.youtube.com/watch?v=yFFpJW0j5z0 )which posits that professional players don't know how to make a fun game because they are concerned with minute details of mechanics and balance, and the vast majority of a game's potential audience want a fun experience in single- or multiplayer. So if you really laser in on the pro-gamer experience, you're creating a niche experience that won't be popular in the wider market -- and hardcore players will turn literally anything (Minecraft, Roblox, Excel) into an esport anyway.