does this require Half Life, Counter Strike, Left 4 Dead or Team Fortress 2 content?

Having to get it may seem tedious, but its well worth it if you intend on playing many other maps.

Well in a way, yes. See, garrys mod is a Source game, as in (Source engine) that valve uses. So people started to use assets from other source games, such as half-life, TF2, Counter-strike, portal, etc. Your not downloading the game itselfe just the textures&models.

apparently its a whole other game?

Tell me if it helped

h ttps :// www.youtube.c om/watch?v=yaL7gISscEY

Just delete the spaces

The source for counter-strike is on a website, you must download it then simply exract and put the file were it belongs. (people worry eveytime i say you have to download something. Do not worry, this cannot give you a virus unless it asks for permission to run, even so if you delcine permission to run your safe. look it up if you have to. #InternetSafety) Its good that you have this, because many thousands of maps and servers use these textures. If your confused about a step just ask. Here is a very easy and quick totorial on how to get this: https://www.youtube.com/watch?v=yaL7gISscEY

is that something i can get here on steam? the counter strike source?

Having skybox issues? For this map make sure you have counter-strike source installed, if your still haveing problems you can DM me through discord useing this channel: https://discord.gg/6HEarKv

when i get on it, the sky gets very glitchy

Keep an eye out for the dumpsters. (;