I remember that mission but not that rat. 
Funny mod!
Don’t know if mice have room in BM, you have already headcrabs, snarks and cockroaches…
there’s already a good amount of critters
What’s this mod?
Thanks!
its not thats actually a easter egg, shoot the center dot.
We need a new fgd now
That won’t… fix anything though… The FGD just tells Hammer what entities it can use, adding new things to it doesn’t magically make them work ingame, they still have to be coded and compiled into the client and server DLLs. There’s an FGD entry for an npc_zombie_grunt, that doesn’t mean it’s actually been implemented in the game.
Forget about the rats, cockroaches, leeches, and wombats! We are cutting our losses and pulling out!