Counter-terrorists, in the time allotted to them, are building, on the site designated for this, a base for defense against zombies.
Zombies are terrorists who, until the end of construction, can only watch, from their spawn, how the construction is going. When the construction time ends, the zombies are released and the bases of counter-terrorists are stormed.
If zombies are killed, he is reborn on his spawn. If a counter-terrorist dies, he waits until the end of the round. If the counter-terrorists will survive until the end of the round, then they will win.
Such servers use maps whose name begins with "bb":
