One of the best GDQ runs I've ever seen was one of the FFVII speed runs. This is a game that normally takes like 50 hours to complete start to finish. The RNG of the game is able to be manipulated by keeping the number of steps taken by the player absolutely perfect. This is a "speed run" that they play without any kind of tools or cheats for hours and the entire time they're keeping the exact number of steps taken through different levels on perfect track to be able to beat the game without spending dozens of hours training their characters.
I recently watched the fallout anthology run and some of the things the speed run community have discovered are amazing.