There is something like that out there, called Ambush (I believe, starts with A at least)
You spawn as a human, and have to survive and fight off waves of aliens, starting at grangers, and progressing upwards till you are being choked by like 40 tyrants (as the entire alien team are bots).
I believe rotacak made a map for it, other than that I have no clue as to who did it.