Speedrunners are playing the game manually, and sharing the tricks they find for how to exploit game mechanics to speed things up. There exist something called

Speedrunners are playing the game manually, and sharing the tricks they find for how to exploit game mechanics to speed things up. There exist something called TAS (tool-assisted speedrun) where you use an emulator with save states and either slow motion or the ability to advance frame-by-frame in order to construct the "ideal" run, but runs constructed these ways generally aren't actually playable by hand because they rely too much on frame-exact timing.