Well, did valve actually make any of them or did they just buy IP that already existed?

Half life they did, but the rest no.

They actually made cs tf and dota 2

IKR

Portal 2 coop ofc

Portal 2 for the win.

I don't think that's true. All 3 of them were mods that valve then ported. CS and TF were both Half-Life mods, dota was a wc3 mod.

As far as I know the only original games they ended up making were Portal and Half-life.

left 4 dead was a game they made too (although it was inspired by the team fucking around in cs)

Portal was a concept by another game company that Valve expanded on.

CS was a mod of Half-life, but from the mod they have heavily developed on it, improving it, and making it their own.

dota was originally a collection of a shit ton of warcraft mods, that later bred "Dota allstars" or some shit.

Tf classic was based off a quake mod back in 96'.

And so on and so forth.

The important thing to note, they dont just buy the idea, the often hire the lead modders (if there are more than one) to help develop it. So while I agree it's not there original concept, they promote the people who did create it by giving them a job. So the games are made by valve, in one way or another.

Half-Life Deathmatch best game ever

Welp the only thing i can say is...

VOTE GABEN FOR PRESIDENT (if he runs for president that is)

XD