Can we use half-life sounds?

[Gamemaker]

Alright folks, I uploaded both, RF and HL1 sound effects.

[bernie]

@gamemaker
Do you realise that by putting those files up for download YOU are breaching their copyright and you openly state they are half life sounds.

[Gamemaker]

I just wanted to prove.

[MakerOfGames]

It doesn't matter if you want to prove it or not, it's illegal.

So what does that mean if you make a game with copyrighted sounds unknowingly? I mean, I don't want to make a good game on my own and find out my gun sound effects were copyrighted when lawyers come knocking on my door.

[Humpty]

@MakerofGames:
Pehaps with a decent mic and good software you could say psssssshuooooouhgkggh into the mike and then distort it. ... it may sound good. There is your laser. Shotgun: Salm something solid yet hollow real hard and sharp then distort that.

These sounds may come out pretty good.

I can recall watching some making of for a disney movie. The sound guys use some machine for the sound of wind and rain. It was like leather being rubbed against leather as they rotate a arm / pivot. The makers of the movie at hand dragged a boxing bag up and down the hall to make thier wind sound.

I believe with no way to back it up that a lot of the sounds that you hear aren't actually the sounds they are meant to be because once recorded they don't sound the same as they do in real life.

Question to OP and others:
How many of the sounds appear to actually be a copy of potentially copyrighted materials?