Yes it is gmod. And if you do want to know the map is called "LV-426" so you are right and because it really was one of the only alien maps for source(it was a CSS Zombie mod map) i could find. And well there was one AVP game that the famous LV-426 or Acheron was the setting and it was "AVP Classic 2000". But i could be wrong i would have to play the game again.
Is it Garry's mod or the KF's Aliens TC?. The files' name suggest it takes place on Acheron and no AvP game took place there so my bet goes on Gmod.
Yes it is gmod. And if you do want to know the map is called "LV-426" so you are right and because it really was one of the only alien maps for source(it was a CSS Zombie mod map) i could find. And well there was one AVP game that the famous LV-426 or Acheron was the setting and it was "AVP Classic 2000". But i could be wrong i would have to play the game again.