Below you will find a video of me playing through the Low% route to demonstrate how to perform the glitches allowing you to finish the game while only collecting the Slingshot, all while giving tips on how to finish some challenging arenas, particularly the last few ones. (Check YT description to use chapters)

Low% is also doable on an NG+ file, but you need to complete a regular NG Low% file first to spawn in an NG+ game without any abilities.