Hiya! While I work on a proper speedrunning tutorial, I'll link some stuff I used while learning/running the game:

GoldSrc Package: https://forums.sourceruns.org/t/goldsrc-package-2-3/2634

Demo Recording Guide from HL1 Community: https://www.speedrun.com/hl1/guide/m3lo4

ovvytec's Ending 1 Segmented run:

Mod Link: https://www.moddb.com/mods/afraid-of-monsters-dc

I'll absolutely flesh this out, but this should get you going in the right direction.

Things to watch out for: Make sure fps_max = 100 Make sure the bhop cap is disabled: bxt_bhopcap 0 Use "bxt_autorecord run" to record demos. Make a save in front of the bathroom stall. To change difficulty, do "skill X" in console. X being 1, 2 or 3. 1 Is Easy, 2 is Normal, and 3 Hard. DO NOT do this in the middle of a run. Do it while setting up save files though.