accessing HL2 maps, and setting up a guard

[salad]

First off, this is my first post. Please bear with me. =]

I'm trying to set up a combine gate/barrier where the guards respawn until the player sets off a certain trigger.
After a bit of exploring, I found an identical setup in the c17_4 map (I forget the exact name)
However, I can't find this map anywhere in my steam folder. So, I have a few questions.

1. Where are the HL:2 map files found?
2. Do I need a special tool to decompile them?

failing that, can someone give me a rough idea of how to set up the scenario I'm talking about?

Thanks

 

[Barnz]

You can find the map files (*.bsp) in "half-life 2 content.gcf" (use GCF Scape to open/extract *.gcf files). You need a map decompiler (you can get one from VDC [1]) to decompile compiled map files.

As for the respawn stuff, use npc_maker (maker_001). For example: Player enters the trigger_once zone and triggers the "maker_001" entity. Then "maker_001" entity (chance frequency for better results) starts to spawn Combine Soldiers (and continues, until you find a way to close it). When player reaches the second trigger_once, it triggers "maker_001" entity again to stop it.

developer.valvesoftware.com [1]