Game guide

Headcrab Infection Guide: Two sides, two completely different goals

Headcrab Infection

BlazeProtocol, Playing 44, Rating 60.5%

Creator BlazeProtocol

Playing 44

Rating 60.5%

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About

Overview

Headcrab Infection is a Roblox horror survival game inspired by the Half-Life series, where up to 30 players fight across a sprawling research facility as either humans trying to escape or Xen aliens trying to stop them. This guide covers how both sides play, how to progress your character, and what to work toward as you put more time in.

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What is on this page

Contents

01 Two sides, two completely different goals Table 02 Surviving and escaping as a human Step 03 Headcrab tactics: hunting and mutating Tips 04 Playing as a Baby Headcrab Step 05 Events: how they work and what they reward Summary 06 Leveling up and what to aim for Check 07 Weapons by category Table 08 Glossary Words 09 Common questions FAQ

Two sides, two completely different goals

Table

In short Pick a side and understand its win condition before anything else.

Every match splits players into human factions and Xen alien teams. Humans want to survive and escape the facility; Xen aliens want to hunt them down. The controls, weapons, and moment-to-moment decisions are entirely different depending on which side you land on.

Survivors	armed with a Crowbar and a G17 pistol, goal is to escape the facility alive
HECU / Black Ops	human soldiers with helmets that block Headcrab infection, goal is to eliminate alien threats
Headcrab	Xen alien that instantly kills by leaping onto an unprotected human's head, then controls the body as a zombie
Headcrab Zombie	the infected human body, playable by the Headcrab player, can mutate further over time
Baby Headcrab	cannot infect anyone, but is one of the fastest characters in the game and supports the Xen team
Pit Drone	the only playable Race-X alien currently, fast with both melee and ranged attacks, and is extremely dangerous to Headcrabs

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Surviving and escaping as a human

Step

In short Staying grouped and finding a keycard are the two things that matter most as a Survivor.

Survivors start with weak weapons and face a steep learning curve. Sticking with experienced players — especially Security Guards, who have reached at least Global Level 40 — gives you cover while you get your footing. Avoid picking fights until your loadout improves.

Stay with the group more players means more eyes and more weapons; lone Survivors are easy targets for Headcrabs and zombies
Find a keycard Security Keycards spawn on the facility's top floor and are required to open the blast door leading to the elevators and eventually the escape route
Unlock the Deagle at Character Level 10 you get access to the Deagle, which deals 58 damage per hit and can kill a Headcrab in two shots; before that, avoid direct confrontations
Handle Headcrabs at range any firearm works, but high-damage weapons like the Deagle or Colt Python drop a Headcrab quickly; explosives are even better since splash damage hits even on a near-miss
Watch your head if you are playing as a Survivor (not HECU or Black Ops), you have no helmet, so a Headcrab that lands on your head kills you instantly
On the surface, keep moving in groups the HECU, Black Ops, their turrets, and the Gargantua are all threats even after you reach the outside

Headcrab tactics: hunting and mutating

Tips

In short A patient Headcrab that blends in with the Xen crowd is far more dangerous than one that rushes alone.

Headcrabs have low health and are easy to hit, so your power comes entirely from the instant-kill leap — and that only works on humans without helmets. Once you successfully infect a host, a 30-second animation plays during which you are immune to all damage, and then you take control of the body as a Headcrab Zombie.

Tips worth knowing

Follow a crowd of Xen aliens toward humans rather than approaching alone — humans focused on other threats are easier targets
Jump when the human is looking away or occupied with someone else — there is a cooldown between jumps, so make each one count
Headcrabs cannot infect Pit Drones; a leap against one deals only 35 damage, so avoid engaging them directly
After becoming a Headcrab Zombie, survive for 150 seconds in one life to mutate into a Gonome, then eat 35 pieces of flesh from dead bodies to reach Mr. Friendly

Playing as a Baby Headcrab

Step

In short Baby Headcrabs cannot infect anyone, but used correctly they speed up your team's kills and earn you steady experience.

When a Gonarch is alive, a prompt appears in the bottom-left corner of your screen letting you choose to become a Baby Headcrab. You can hide it with the X button on the prompt, or turn it off permanently in settings and re-enable it whenever you want. If you stay alive for two minutes as a Baby Headcrab, you mature into a full Headcrab and regain the ability to infect humans.

Stick near a Fast Headcrab Zombie if you land one hit on a human, the Fast Zombie can finish them in two more hits when the human is below Level 80
Stay close to the Gonarch dealing any damage to a human before the Gonarch kills them earns you an experience assist
Keep attacking damaged humans every hit interrupts the human healing process, keeping them vulnerable for your teammates
Use your lunge to stay mobile Baby Headcrabs have one of the fastest movement speeds in the game, so use it to dodge fire and reposition constantly

Events: how they work and what they reward

Summary

In short Event badges unlock exclusive characters, so understanding the format before an event starts puts you ahead.

Headcrab Infection has run several limited-time events, each structured around waves of enemies fought in a dedicated arena. Past events are no longer available, but the format is consistent enough that knowing how they work prepares you for future ones.

Arena access　events use special teleporters placed around the facility and surface; activating them takes you to the event arena
Wave structure　enemy counts increase each wave and new enemy types appear every few waves; coordination across all players is required because enemies have high health pools
Death penalty　in the 2024 Halloween Event, dying sent you back to Wave 1, making survival as important as dealing damage
Damage threshold　some events require you to deal a minimum percentage of the final boss's total health to qualify for the badge reward, not just survive to the end
Exclusive characters　completing event badge requirements has unlocked characters unavailable anywhere else, such as the reward tied to the 2024 Halloween Event badge
Group size cap　the 2024 Halloween Event ran groups of up to 8 players per arena, with a maximum of three arenas active at once

Leveling up and what to aim for

Check

In short There are two separate level tracks to work on, and weekends give you the fastest gains on both.

The game tracks a Character Level for each individual character you play and a Global Level that accumulates across everything you do. Both cap at 100 and each has its own badge. Playtime badges display next to your name in the players table during a match, so they are visible to everyone in your server.

Play during weekends the game awards 1.5x experience on weekends
Character Level 10 unlocks the Deagle reaching it on a human character gives you access to a weapon that deals 58 damage per hit
Character Level 20 unlocks the P220 a stronger alternative to the starting G17 with faster fire rate
Survive 150 seconds as a Headcrab Zombie in one life to mutate into a Gonome dying resets this timer, so staying safe matters
Reach Global Level 100 and Character Level 100 on any one character to earn their respective badges
Playtime badges at 1, 10, 50, and 100 hours appear next to your name for others to see the Pro badge at 100 hours is held by very few players

Weapons by category

Table

In short Knowing the damage and magazine size of each weapon helps you decide when to shoot, when to switch, and when to run.

All weapons in the game are balanced around gameplay rather than real-world accuracy. Ammo is replenished from ammo boxes found in the facility.

Weapon	Damage per hit	Magazine size	Unlocked by
Crowbar	24	N/A (melee)	All players from the start
G17	15 (15 headshot)	20	All Survivors from the start
Deagle	58 (2.4x headshot multiplier)	7	Character Level 10
P220	18 (27 headshot)	15	Character Level 20
G18	8 (no headshot bonus)	12	Survivors
Colt Python	55 (7.2x headshot multiplier)	6	Survivors
USP-S (dual)	28 (56 headshot)	16	Black Ops Assassins
AR-10	21 (31 headshot)	20	Survivors
C727	19 (28 headshot)	25	Survivors
MP5	20 (42 headshot)	30	HECU
RPG	Explosive splash	N/A	Survivors
M79 Grenade Launcher	Explosive splash	N/A	Gamepass

Community strategy ideas

Community

These ideas and tips come from people playing the game. Share your discoveries too!

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Glossary

Global Level: A level that increases across all characters you play, separate from any single character's level, with 100 as the cap.
Character Level: A level tied to one specific character; reaching Level 10 unlocks the Deagle, and Level 20 unlocks the P220.
Headcrab Zombie: The playable infected human body that a Headcrab player controls after a successful head-leap; it can mutate into a Gonome after surviving 150 seconds.
Gonome: The first mutation stage of a Headcrab Zombie, reached by surviving 150 seconds in a single life as a zombie.
Mr. Friendly: The final mutation stage, reached after a Gonome eats 35 pieces of flesh from dead bodies.
Gonarch: A large Headcrab variant whose presence on the map activates the option for Headcrab players to become Baby Headcrabs.
Pit Drone: The only currently playable Race-X alien, highly dangerous to Headcrabs due to fast attacks and both melee and ranged options.
Security Keycard: An item that spawns on the facility's top floor and is required to open certain doors, including the route toward the escape exit.
Keycard-operated blast door: A door on the facility's top floor that requires a Security Keycard to open, leading to the elevators that connect to the lobby and the escape route.
HECU: Hazardous Environmental Combat Unit — a human soldier faction whose helmets block Headcrab instant-kill infection.
Black Ops: A human covert faction that also wears helmets, protecting against Headcrab infection, and uses SMGs and silenced pistols.

Common questions

FAQ

Can a Headcrab kill me even if I have a helmet?

Helmets protect against Headcrab instant-kill leaps, but only HECU and Black Ops players wear them. If you are playing as a Survivor, you have no helmet and a Headcrab landing on your head kills you immediately.

How do I escape from the facility?

Find a Security Keycard on the top floor of the facility and use it to open the keycard-operated blast door leading to the elevators. Make your way to the surface escape door near the dam tunnel. Threats like the Gargantua, HECU, and Black Ops are active on the surface too.

How do I become a Baby Headcrab?

A Gonarch must be alive for the option to appear. When one is, a prompt shows up in the bottom-left corner of your screen. Click it to transform. If the prompt is in your way, press the X on it to hide it, or disable it entirely in your settings and turn it back on whenever you want.

I died during the event — do I lose my progress?

In the 2024 Halloween Event, dying sent you back to Wave 1, so surviving every wave without dying was essential to reach the final boss and earn the badge.

Updated Oct 31, 2026
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Headcrab Infection BlazeProtocol, Playing 44, Rating 60.5%

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