Lockdown mod for Half-Life 2

MOD IS DEAD intro : You are a P.I.T. Marine (Point Insertion Team) sent in to eliminate an mass threat, Currently in transfer you are briefed the following; "the enemy (origin unknown) is lead by a mother creature that spans roughly 30 feet tall. It constantly mothers smaller creatures that terrorize and destroy, and all the creatures are highly lethal. the mother is slow moving and can take quite a punch, it attacks by spitting acid at long ranges that can penetrate your heavy armor. the smaller ones are much more aggressive and versatile, they are about 10 feet tall and are quick moving, and able to leap large distances quickly. be prepared for a serious challenge" as you exit the APC you enter a city, torn up, and smoking of ruin. you lock and load your rifles, and move out in a team. as you near the center of the city one of your comrades quickly shouts something, but it came out in a blur and you were unable to understand. suddenly gunfire bursts out and as you turn you...