How to edit already existing Half-Life maps? Created 4 years ago2020-05-20 06:20:20 UTC by Yes, Please

Apologies if this has already been asked but I'm making a mod that's general quality-of-life changes to the original game (fixing the Barney intro plothole, security guard and HECU zombies, etc) and is there any way to gain access to the already existing Half-Life maps in Hammer Editor because I couldn't find anything on the matter.

In a word, no. You can decompile the existing maps but this is more for the purpose of reference. There is no way to recompile them into a playable map.

The only option would be to decompile the maps for reference, and then completely rebuild them, which I would say is far more hassle than it is worth for what you're suggesting, personally.

i saw a couple of tools that can edit already existing entities in a bsp map

There's a process called rip-enting, where you can only change the entity data in the BSP.
However, you cannot exactly open that up in Hammer, it's all text editing.