Something I felt needs addressed due to seeing many invalid fingers of blame being pointed. Only a fool would choose to blame Valve or Garry when sometimes it's neither one's fault. To find "fun" in blaming either side is just down right immature and shows no respect, and no time taken to bother to understand how sensitive coding and programming is.

Whenever Valve updates their "Source Engine", it sometimes causes Garry's Mod to become incompatible and conflict. Basically, it will appear to break, but it's not really broken, it's just expecting different Source Engine version since it's a MOD. Which leads me into the next thing... it's a MOD. Valve isn't responsible for mods, but since it's a product Garry has on Steam, he does get access to the Source Engine code... but he has to wait on that... and that leads us to the next thing... Garry has to wait on this code to be uploaded from Valve. So this is why it takes him some time, because he needs to wait for this code to become available.

Not every Source Engine update coming through Steam will do this to Garry's Mod, just major changes, and it's usually a gamble. A risk we take since it's not on its own engine... yet. Coming in version 13, Garry has stated Garry's Mod will be on its own engine and won't have this problem. Even the current betas are unaffected by this.

This is also why Portal 2 isn't mountable either... it's a different engine, or branch, at least, like both Left 4 Dead games... although progress was being made for the latter. We're starting to be able to mount L4D content and use some of it... just not maps, unless someone, like someone on Face Punch for example, "hex edits" them and fixes up anything that's incompatible. Now the issue with some "infected" models being strange colors I think was a "shader" issue but I don't remember. Guns being bright or shiny might be the "phong". Other items and the survivors are fine.