Hi, news from the newb modder. It probably has tons of issues and isn't done, but I have the majority of the xenomorph base done.
[CREATURE:XENOMORPH]
[DESCRIPTION:A very dangerous creature. They reproduce via facehuggers implanting live hosts with eggs, and the aliens bursting out of the chest. Facehuggers are hatched from eggs laid by the queen.]
[NAME:xenomorph:xenomorphs:xenomorph]
[CREATURE_TILE:'X'][COLOR:0:0:1]
[LARGE_ROAMING]
[LIKES_FIGHTING]
[EXTRAVISION]
[BIOME:SUBTERRANEAN_CHASM]
[UNDERGROUND_DEPTH:1:3]
[OPPOSED_TO_LIFE]
[POPULATION_NUMBER:10:40]
[CLUSTER_NUMBER:5:15]
[CANOPENDOORS]
[ALL_ACTIVE]
[CAN_LEARN]
[NO_SLEEP]
[NOBREATHE]
[CARNIVORE]
[HOMOTHERM:10028] <--- should be 60 degrees fahrenheit
[USE_MATERIAL_TEMPLATE:SINEW:SINEW_TEMPLATE]
[TENDONS:LOCAL_CREATURE_MAT:SINEW:200]
[LIGAMENTS:LOCAL_CREATURE_MAT:SINEW:200]
[HAS_NERVES]
[USE_MATERIAL_TEMPLATE:BLOOD:BLOOD_TEMPLATE]
[BLOOD:LOCAL_CREATURE_MAT:BLOOD:LIQUID]
[MAXAGE:10:30]
[CASTE:FACEHUGGER]
[CASTE_NAME:facehugger:facehuggers:facehugger]
[POP_RATIO:100]
[NO_GENDER]
[CASTE:DRONE]
[CASTE_NAME:xenomorph drone:xenomorph drones:xenomorph drone]
[MALE]
[POP_RATIO:0]
[CASTE:HUNTER]
[CASTE_NAME:xenomorph hunter:xenomorph hunters:xenomorph hunter]
[POP_RATIO:0]
[NO_GENDER]
[CASTE:QUEEN]
[FEMALE]
[CASTE_NAME:xenomorph queen:xenomorph queens:xenomorph queen]
[POP_RATIO:0]
[SELECT_CASTE:DRONE]
[SELECT_ADDITIONAL_CASTE:HUNTER]
[SELECT_ADDITIONAL_CASTE:QUEEN]
[BODY:HUMANOID:HEART:GUTS:BRAIN:SPINE:NECK:SKULL:TAIL]
[SELECT_CASTE:FACEHUGGER]
[BODY:FACEHUGGER_PROBOSCIS:2SKIN_FLAPS:8LEGS:TAIL]
[SELECT_CASTE:ALL]
[BODY_DETAIL_PLAN:CHITIN_MATERIALS]
[BODY_DETAIL_PLAN:CHITIN_TISSUES]
[BODY_DETAIL_PLAN:EXOSKELETON_TISSUE_LAYERS:CHITIN:FAT:MUSCLE]
[BODY_DETAIL_PLAN:STANDARD_HEAD_POSITIONS]
[SELECT_CASTE:DRONE]
[SELECT_ADDITIONAL_CASTE:HUNTER]
[SELECT_ADDITIONAL_CASTE:QUEEN]
[ATTACK:PUNCH:BODYPART:BY_TYPE:GRASP]
[ATTACK_SKILL:GRASP_STRIKE]
[ATTACK_VERB:punch:punches]
[ATTACK_CONTACT_PERC:100]
[ATTACK_FLAG_WITH]
[ATTACK_PRIORITY:SECOND]
[ATTACK:KICK:BODYPART:BY_TYPE:STANCE]
[ATTACK_SKILL:STANCE_STRIKE]
[ATTACK_VERB:kick:kicks]
[ATTACK_CONTACT_PERC:100]
[ATTACK_FLAG_WITH]
[ATTACK_PRIORITY:SECOND]
[ATTACK:BITE:BODYPART:BY_CATEGORY:MOUTH]
[ATTACK_SKILL:BITE]
[ATTACK_VERB:bite:bites]
[ATTACK_CONTACT_PERC:100]
[ATTACK_entry_PERC:100]
[ATTACK_FLAG_EDGE]
[ATTACK_PRIORITY:MAIN]
[ATTACK_FLAG_CANLATCH]
[ATTACK:SLASH:BODYPART:BY_TYPE:TAIL]
[ATTACK_SKILL:STRIKE]
[ATTACK_VERB:slash at:slashes at]
[ATTACK_CONTACT_PERC:100]
[ATTACK_entry_PERC:100]
[ATTACK_PRIORITY:MAIN]
[SELECT_CASTE:HUNTER]
[AMBUSHPREDATOR]
[NATURAL_SKILL:AMBUSH:8]
[NATURAL_SKILL:BITE:10]
[NATURAL_SKILL:STRIKE:5]
[BODY_SIZE:0:10:10000]
[BODY_SIZE:0:40:50000]
[BODY_SIZE:0:80:85000]
The materials for their skin and stuff were taken from antmen. Xenomorphs are said to have a material similar to chitin for skin, so it's all cool. I'm not entirely sure what I have even works yet, but that's part of the modding process.
Some of the lines were incorrectly spaced, if you know how to mod then you'll see some strange, random spaces.