I made this hack 16 years ago, formerly named "HL Traps". Almost everything was changed into climbable vines/ladders. I updated it recently, and made a TAS.
It's hard to play without savestates, but it's doable. No glitch required.
IPS patch download: https://mega.nz/file/PxF1kKaS#Ds2i-K0N4Yfc...