They can leap at enemies and can dodge most attacks, as well as parkour up buildings and objects. These Zombies have a feature that can prove difficult to counter. They do have their own Headcrab that shares the same traits, and will detach the same way a regular Headcrab does. They are too, easily killed with props and explosives, but can not be torn in half. Unlike regular Zombies, these Zombies have a speed boost, at the cost of health. Though, the Headcrab that goes with this Zombie is seen in the Vorticough achievement earlier in the game. These Zombies are introduced in Ravenholm along with the Poison Zombie. Overall, they are not much of a threat with the right tools. Dispite being weak to these hits, they do pose a threat when in groups or in tight corridors. A cinderblock thrown with the Gravity Gun will kill one quickly, an explosive like a grenade or barrel will kill one too. They do have a weakness when it comes to heavy props or explosives. Also, killing them by shooting them in the chest will cause the Headcrab to come off and attack you. Sometimes, they can lose their legs and still crawl toward you. They have a standard melee attack, so they are easily dispatched with explosives, props, and guns. This standard, run-of-the-mill enemy is one of the most frequently fought enemies in the game (next to Combine). The first type of Zombie you’ll meet is the Classic Zombie. So, now that you know a little story, lets get down to buisness. I would assume they came to Earth after the Combine took over, or were brought with the Combine. Now there are 3 different Zombies with their own Headcrabs. In Half Life 1, there was only the one Zombie and Headcrab. Not being completely attached to the host, it will detach itself if the host takes critical injury, and will seek out a new one. When a Headcrab latches on to a new host it will couple with their head and begin to take over their bodily functions and control the host. They then sought out hosts to latch on to and procede through the facility in search of food. They came to Earth through the portals opened accidentally by Gordan Freeman with the help of Gman. Headcrabs are the start and cause of infection. Tread lightly (even more careful in Ravenholm ), for when you see a one, their will be others nearby. Though not much of a threat alone, they can be difficult in hordes. The basis behind the Zombie is to be used as a flexible enemy type for you to fight, coming in different varieties, and have a wide range of challenging abilities. They have a alignment of their own, attacking enemies like Combine and Anlions, instead of helping them fight Rebels and overall, you. Zombies have been a trademark enemy of Half-Life’s heros and NPCs.
A guide on Half Life’s Headcrabed population and how to defeat them, know them, and take advantage of their faults.