Introduction
Creatures in ALIEN RPG Evolved Edition work best as forces that change the situation around the crew. A parasite makes a rescue urgent. A hive makes a location hostile. An animal makes a route unsafe. The creature matters because the players must decide what to protect, abandon, investigate, contain, or escape.
This guide covers the whole creature toolkit in one place: how to build a creature situation, how the Xenomorph XX121 lifecycle escalates stage by stage, how Neomorphs and other extrasolar species differ, which numbers are worth knowing before you run them, and how to turn a hive into a location instead of a boss room. The core book stays the source for full attack tables and special rules at the table.
The Xenomorph is scarier as the consequence of a bad situation than as a scheduled encounter. The book's own advice to characters who see one is "run," and a Game Mother who builds every scene around a fight is ignoring the best line in the chapter.
Hot Take
Stat blocks get memorized long before behavior does, and that ordering makes for worse creature scenes. A Game Mother who can recite a Drone's Armor Level but has not decided what a search pattern, a stalking Scout, or a molting Queen actually does to the fiction ends up running every stage as the same fight with a bigger health total.
Lead with what the crew can observe: a warm hiding spot, a silent approach, a hive that quiets when the Queen is near. The dice only matter once the crew has already had to decide what that evidence means.
Build a Creature Situation
Do not begin with "the creature attacks." Begin with a problem that the creature has made harder:
- A worker is missing behind a sealed door.
- The crew's route crosses a territorial habitat.
- The air, supplies, or a critical worksite may be contaminated.
- A corporation wants live evidence that no one can safely collect.
- A survivor knows something vital but cannot leave their current location.
Then give the creature a purpose. It may be hunting, nesting, guarding territory, spreading through an environment, collecting hosts, or reacting to a disruption. That purpose tells you how the situation changes when the crew waits, retreats, makes noise, or chooses a different route.
When you need the mechanics, use the Evolved Edition core book at the table. In preparation, define the scene by its pressure and the information on offer:
- Name the immediate problem. A sealed door, a trapped survivor, a failing generator, or a lost route gives the crew a reason to act.
- Choose the creature's purpose. It is hunting, nesting, guarding, collecting hosts, escaping, or responding to a disturbance.
- Place evidence before contact. Sound, damage, movement, a missing person, or an altered room should point toward a choice.
- Track what changes if the crew delays. The route closes, a resource runs out, another person becomes exposed, or the threat changes position.
- Let the crew's response reshape the scene. A successful escape, clever lure, or costly rescue should matter even if the threat remains alive.
In stealth mode, hidden movement and partial information support a cat-and-mouse scene. Keep the players informed about what their characters can observe, and hold back only what they have not earned. For a broader preparation framework, use the Complete Game Mother Guide, and pace the reveals with the Running Horror Guide.
Set a Spoiler Boundary First
The lifecycle is major setting information. Before play, decide whether the group wants discovery to happen through the characters' experience or whether everyone is comfortable treating the lifecycle as established knowledge. That decision matters most in a Cinematic scenario, where a first clue can land harder than a complete explanation.
Use a simple disclosure ladder:
| What the crew sees | What it tells them | What it lets them do |
|---|---|---|
| An altered room, missing person, or strange residue | Something has changed the environment | Search, retreat, seal a route, or call for help |
| A living host or active containment problem | The danger has a time-sensitive human cost | Rescue, investigate, quarantine, or make a hard trade |
| A moving threat or breached safe area | The threat can reach them | Hide, reroute, arm themselves, set a trap, or flee |
| A hive or coordinated adults | The problem is organized and expanding | Extract survivors, destroy evidence, contain the site, or escape |
Secrecy should never remove choices. A clue does not need to explain every cause to make a door, a victim, a route, or a countdown matter.
The Xenomorph Lifecycle, Stage by Stage
The core book describes Xenomorph XX121 as an endoparasitic lifeform that shifts from egg to Facehugger to Chestburster to adult "and beyond" before the cycle begins again. It numbers six stages, each with named forms. Treat them as a rising set of stakes rather than a required scene order.
| Stage | Forms | What changes at the table |
|---|---|---|
| Stage I | Ovomorph (egg), the Queen's egg | The threat is dormant or hidden, but the space is no longer safe to search casually. |
| Stage II | Facehugger, Praeto-Facehugger, Royal Facehugger | The danger becomes immediate, intimate, and focused on one potential host. |
| Stage III | Chestburster, Bambi Burster, Imp, Queenburster | The cost becomes visible and irreversible, and the scene turns to pursuit or containment. |
| Stage IV | Drone, Scout, Stalker | A lone young adult controls space, hunts, and starts gathering hosts. |
| Stage V | Soldier, Worker, Sentry | The hive mind takes hold and the aliens specialize into roles. |
| Stage VI | Praetorian, Charger (Crusher), Queen | The danger becomes a system with leaders, guards, and mass egg-laying. |
The book treats anything past Stage VI, such as Empress or Queen Mother stages, Palantines, or an Alien King, as rumor that has not been confirmed. You do not need every stage in one session. An investigation can begin after an earlier stage has already passed, and an escape scenario can use an adult without explaining where it came from.
Stages I to III: Egg, Facehugger, Chestburster
Ovomorphs stand 0.6 to 1.2 meters tall and sense movement. If a potential host is within Short range, the Game Mother rolls a stress die each round to see whether a Facehugger is released, and anyone at Adjacent range must roll MOBILITY to avoid disturbing the egg. Eggs come either from a Queen or from ovomorphing, where a lone Drone cocoons a host and turns it into an egg over roughly 24 to 36 hours.
A Facehugger that succeeds with its final attack leaves the victim broken and implanted. Within one shift the Facehugger dies and falls off, and after another shift a Chestburster is born, killing the host. Removing a Facehugger kills the host unless it is first immobilized by extreme cold. The book lets hypersleep, stasis, or a host's health slow or speed gestation, and leaves the final pace to the Game Mother.
Stage III varies with the host and the seed. A Bambi Burster comes from a quadrupedal host, an Imp is the young form of a Praetomorph, and a Queenburster gestates over days instead of hours. Newborns are at their most vulnerable, flee to hide and eat, and reach Stage IV within one shift. Anyone who witnesses a birth for the first time makes an immediate panic roll.
Stages IV to VI: Adults and the Hive
Stage IV aliens operate outside the hive mind. The Drone is the stealthy ambush hunter behind the Nostromo incident and gets a Silent Assassin ability that imposes -2 dice on OBSERVATION rolls to spot it in stealth mode. The Scout searches for hosts and alerts the hive. The Stalker is the aggressive adult Praetomorph and appears to be an evolutionary dead end.
When a Queen's influence takes hold, Stage V aliens molt into specialists. Soldiers attack in numbers and can paralyze prey with a tail barb to carry back to the hive. Workers build and maintain the resin structure and flee from threats. Sentries guard the inner hive and the Queen. Stage VI holds the hive's leaders. Praetorians and the tank-like Chargers appear only when a Queen exposes her Soldiers and Sentries to Royal Jelly, while the Queen herself, at six meters or more, grows from a Queenburster and is the only form that lays eggs in large numbers.
Use Each Stage as a Different Problem
Give each stage a job in the fiction instead of treating the list as a combat catalogue.
| Stage or condition | Strong encounter role | Meaningful crew decision |
|---|---|---|
| Ovomorph or suspected nest | Discovery and containment | Do we inspect, mark the route, burn it, or keep moving? |
| Facehugger threat | Rescue under pressure | Do we risk a direct intervention, isolate the victim, or look for cryo equipment and lose time? |
| Incubation aftermath | Investigation and triage | Who learns the truth, and what does the crew do with limited time and incomplete information? |
| Newly emerged creature | Pursuit and escape | Do we split up, lock down a section, lure it away, or abandon the objective? |
| Lone adult | Territorial predator | What route, resource, or person is worth exposing the crew to it? |
| Hive | Infiltration, extraction, or containment | Is the goal rescue, evidence, sabotage, or survival, and is that goal worth the risk? |
Xenomorph Rules and Stats Worth Knowing
You do not need to memorize a stat block, but a few rules change how you plan a creature scene. Xenomorphs have no attributes: they roll dice equal to a skill level, never push, and get one full turn per point of Speed. They pick signature attacks from a D6 table instead of taking normal actions, never dodge or block, and are immune to stun damage unless stated otherwise. At zero Health, most adults roll on their own table, where results range from a feigned death to fleeing wounded to being torn apart. A single stretch of rest restores all their lost Health.
Xenomorph XX121 also has an Acid Splash rating. Damage other than fire splashes everyone at Adjacent range and the floor, and the acid keeps eating through armor each round until a roll deals no damage. The species ignores cold and vacuum, shrugs off radiation, and is not hindered by darkness in stealth mode.
| Form | Speed | Health | Armor Level | Acid Splash |
|---|---|---|---|---|
| Ovomorph | 0 | 2 | 0 | 4 |
| Chestburster | 2 | 2 | 0 | 4 |
| Drone | 2 | 7 | 2 (1 vs fire) | 8 |
| Scout | 2 | 5 | 2 (1 vs fire) | 8 |
| Soldier | 2 | 8 | 2 (1 vs fire) | 10 |
| Worker | 1 | 4 | 1 (0 vs fire) | 6 |
| Sentry | 2 | 8 | 2 (1 vs fire) | 10 |
| Praetorian | 2 | 12 | 3 (1 vs fire) | 10 |
| Charger | 1 | 20 | 5 front, 3 other | 10 |
| Queen | 2 | 18 | 4 (2 vs fire) | 10 |
The pattern is the useful part. Fire lowers almost every armor value, the book repeatedly names fire and explosives as the best containment tools, and anything above Stage IV outclasses a civilian crew. The book's optional "Aliens mode" lets a Xenomorph at zero Health simply die when the crew has heavy weapons and faces several of them, which suits a military campaign better than a horror one-shot.
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Make the Hive a Place, Not a Finale
An alien hive is more than a room containing a final monster. The core book describes a resin nest of twisting, confusing tunnels built by Workers, with hot and humid air, cocooned hosts in the walls, Soldiers hibernating in ridges and on the ceiling, and a guarded central chamber where the Queen lays eggs. The book also notes that half a dozen or more Stage IV aliens start acting in unison, and that a hive seems to grow smarter as it grows larger.
That makes the hive a location with several possible objectives. Before sending a crew inside, answer these questions:
- What do they need from the hive right now?
- Who or what can still be saved?
- Which route is known, and what could make it unsafe?
- What evidence shows the hive's scale without fully explaining it?
- What consequence follows if the crew leaves without acting?
That framework lets the group decide whether entering is worth it. If they turn back, the situation keeps changing. If they go in, the hive produces pressure through space, time, and difficult priorities rather than a scheduled reveal. Rival hives also fight each other to kill the other Queen, which gives a campaign a way to change the balance of power without the crew firing a shot.
Alien Species: Choose by Scenario Pressure
The core book's creature chapter covers the Engineers, Xenomorph XX121 and its Praetomorph variant, Neomorphs, and a sampling of other extrasolar species. Variety should change player decisions, beyond just the body count. Start with the story pressure, then pick the species.
| Scenario pressure | Useful creature approach | What the crew must decide |
|---|---|---|
| Containment failure | Xenomorph lifecycle evidence or Neomorph infection | Who is exposed, what gets sealed, and what can be saved? |
| Rescue in a compromised site | Xenomorph territory or hive activity | Is the survivor worth the route, time, and resources required? |
| Frontier expedition | Territorial extrasolar wildlife | Do we cross, distract, detour, or abandon the objective? |
| Colony crisis | An invasive species, damaged ecology, or a food threat | Who bears the cost of quarantine, evacuation, or a risky solution? |
| Corporate job | Creature research, extraction, or weaponization | Does the crew complete the contract, conceal evidence, or refuse the order? |
The creature's behavior should show through its effects: a changed route, a missing worker, ruined supplies, a strange sound, an altered habitat, or a frightened local. Give players enough evidence to choose a response before a full reveal.
| Creature approach | Pressure at the table | Strong scenario goal |
|---|---|---|
| Xenomorph lifecycle | Hosts, containment, stalking, and hive territory | Rescue someone, contain a breach, reach an extraction point |
| Neomorph contamination | Exposure, infected terrain, rapid escalation | Quarantine a site, identify safe ground, survive an evacuation |
| Extrasolar wildlife | Territory, ecology, movement, and resource disruption | Cross a region, protect a settlement, recover equipment, redirect a threat |
When every creature does the same thing, players repeat the same solution. When the pressure changes, the crew has to reassess information, resources, relationships, and risk.
Neomorphs: Contamination and Speed
The core book presents the Neomorph as a separate endoparasitic organism first met by the crew of the USCSS Covenant, the result of Agent A0-3959X.91-15 mutating native fungal and insect life. Neomorphs are eyeless and more animalistic than Xenomorphs, and their yellow blood is not acidic. The book lists five known stages:
- Egg sacs: bird's-egg-sized fungal pods growing in clutches of 2D6, often several per infected area.
- Motes: a puff of near-invisible parasites released when a sac is disturbed. Exposure works as a disease with virulence -2, and a failed STAMINA roll means the next stage begins within one shift.
- Bloodburster: a quadruped that tears its way out of the host, always fatally, and reaches the juvenile stage after a few stretches.
- Neophyte: a juvenile 1.2 to 1.8 meters long that fixes on one prey target and becomes an adult after one shift.
- Adult: a gaunt biped of 2.1 meters or more that hunts with stealth and dies of natural causes within about 24 hours, after which its corpse seeds new egg sacs.
Bloodbursters, Neophytes, and adults can all move an extra zone when they sprint instead of attacking, and the Bloodburster and Neophyte have Speed 3. That changes the scenario:
| Neomorph pressure | Playable result |
|---|---|
| Infected air, growth, or supplies | Surveys, quarantine, protective equipment, and route choices become urgent. |
| Uncertain exposure | The crew must decide who to trust, isolate, treat, or inform. |
| Fast growth and pursuit | Delay is a cost, and a safe room may only be safe for a while. |
| A short-lived adult and renewed contamination | Escaping one creature does not resolve the site-wide problem. |
Use this species for a place that went wrong before the crew arrived. The horror comes from realizing that ordinary exploration procedures may already be inadequate. Fire kills sacs and motes, and liquid nitrogen makes sacs inert until they thaw.
Extrasolar Wildlife: Make the World Dangerous
The other extrasolar species let a Game Mother build danger that is not parasitic, humanoid, or automatically a final confrontation.
- Harvesters: six-legged burrowers of six meters or more that navigate by sonar and grind through farmland, graveyards, and food stores. Bionational shipped them to mining worlds, where they escaped. A sleeping Harvester just under the surface can collapse the ground under a careless crew.
- Lion Worms: eyeless ambush predators of the Zagreus jungle that build traps in their territory and impose -2 dice on OBSERVATION rolls for prey inside it. The pheromones of a rival Lion Worm distract them, and poachers are rumored to smuggle them off-world as pets.
- Tanakan Scorpionids: desert and cave-lake arthropods of Tanaka 5 that hunt at night, swim fast, and carry a venom that can kill quickly without an antidote. Their shells stop knives but not bullets.
- The Swarm: "space locusts" from LV-KR 115 that consume an area, choke anyone inside it, and eat the polymers in armor.
Treat these as ecology first:
- What does the creature need from this habitat?
- What evidence does that leave for the crew?
- Which human activity has disturbed, attracted, transported, or profited from it?
- What local knowledge or environmental tool could change the crew's options?
This supports scenarios where the goal is to cross a dangerous area, protect a settlement, recover equipment, stop a corporate mistake, or survive a disrupted ecosystem. The creature need not be evil or waiting for a fight to be a serious threat.
Reveal Behavior Before Mechanics
Keep the full creature entry in the core book and reveal information in layers. Start with what characters can sense, then show what the creature does, then expose a tactical fact only when the characters have earned it through observation, research, contact, or hard experience.
| Reveal layer | Example information | Why it helps play |
|---|---|---|
| Evidence | Tracks, altered walls, strange spores, a collapsed tunnel, or missing supplies | Creates an investigation and a route choice. |
| Behavior | It nests, follows heat, avoids an area, protects territory, or hunts one target | Lets the crew form a plan. |
| Consequence | A route closes, an NPC is trapped, a resource is contaminated, or time runs out | Makes delay and priorities matter. |
| Mechanics | A roll, defense, or combat result from the core book | Keeps the procedure accurate without turning prep into copied rules text. |
Some behavior details make good earned knowledge. Facehuggers are effectively blind and hunt by sound and heat, so a zone near body temperature gives them -2 dice to OBSERVATION. Drones hibernate in warm places such as near a reactor. Sentries stay in the inner hive unless the Queen leaves. Each of those facts gives a clever crew a plan without making them safe.
The goal is not to make players helpless. It is to let them learn enough to choose what risk they accept, while preserving the details their characters have not discovered yet. Use this guide as a loop: choose the scenario pressure, reveal evidence the crew can act on, let them decide what matters, and use the core book when the resulting situation needs mechanics.
Where To Go From Here
Put a creature situation to work: pace the resulting dread and terror with the Game Mother Resources guide, and run the stress and panic a reveal creates with the Stress and Panic guide.
Source Scope
Rules and setting details in this guide were checked against the ALIEN RPG Evolved Edition Core Rulebook, chapter 10 (Alien Species). Stats are summarized for planning; signature attack tables and full special abilities stay in the book. For the rest of the library, return to the ALIEN RPG Evolved Edition root guide.
