Creature Design Guidelines

Please note: these design guidelines are still being workshopped. They are what I'm using to create monsters internally as of this post. If you're playtesting this with friends, be prepared to make adjustments to the creature's difficulty (tweaking HP, adding a new ability, whatever you need to do) on the fly. 

Size Classes

Creatures come in various sizes; Tiny, Small, Medium (standard/default), Large, and Extra Large. The creature's size class determines everything else about its design, and should be chosen first. Creatures outside this size scope can exist, but should be designed on a case by case basis, because this framework is not intended to be for unique creatures.

Small and Tiny creatures will typically be found in groups. Groups can be operated with each individual creature using its own combat actions, or by combining all their combat actions together and operating them as a Swarm. Tiny creatures should almost always be constructed as Swarms for the sake of encounters. Swarms can be designed as Small, Medium, Large, or Extra Large creatures, following the rules for that size class. Swarms should be given the Double Attack trick (or something functionally identical) as one of their abilities.

HP, Resilience, and DR

HP is a range in direct proportion to a creature's size, unless the GM is designing a swarm of creatures. HP will be a pool of dice and can include flat number modifiers. A modifier should be added to a creature's HP to ensure that it reaches a minimum desired HP level.

For example, a particularly weak creature might use the HP dice base from the size class below it to reflect that it is more frail. A modifier may be added to make sure the lowest possible roll does not fall below the specified range for its size class.

In another example, a GM might want to make sure a very strong individual doesn't fall below a certain HP level within its size class, so a modifier is added to the dice pool to make sure that this desired minimum is met.

Note: Resilience values are complex to calculate and not currently included in this framework. For the time being, treat robots, turrets, and inanimate enemies like any other creature and assign an "armor" for it to get DR values.

Ability Slots

Creatures get a number of "ability slots" based on their size. Abilities include skills and weapon skills, creature attacks, astromancy Disturbances, and tricks. These can be mixed and balanced in whatever combination the GM wants. Creature abilities ignore all prerequisites that players and fully constructed NPCs have. For example, if you want to give a creature Double Attack in one ability slot, you are not required to have the Dueling skill taking up another. 

Tiny Creatures

Whenever possible, tiny creatures should be constructed as Swarms of a larger size.

HP: d4 based, minimum 1

DR: silk or mycelium 

Abilities: 1

Small Creatures

Small creatures should be found in groups but constructed singularly. They can form Swarms of Large size or larger.

HP: d6 based, minimum 4.

DR: Silk or mycelium

Abilities: 3

Medium Creatures

Can appear solitary or in groups, should be constructed as single creatures.

HP: d6 based HP, minimum 8.

DR: any

Abilities: 4

NOTE: Humans being designed as creatures for encounters are considered to be Medium in size. They should be given 3d6 HP with a modifier ranging from 2 to 5 depending on how beefy you want them. Damage Resistance should be calculated from their armor, and they can have 4 abilities following creature rules. More important enemies or NPCs should be fleshed out as full character sheets, and in that case follow those rules and not creature rules.

Large Creatures

Should be in groups no greater than 2.

HP: d8 based HP, minimum of 12

DR: Liquid or ceramic

Abilities: 6

Extra Large Creatures

Should only be seen solitary.

HP: d12 based, minimum of 20

DR: liquid or ceramic

Abilities: 8

Existing Creatures

Star Terror

5 armed, black creature with needle like points at the end of each "arm." Star Terrors are Netheri that live in small groups (3-5). They have a hard but flexible body and can thrive in the vacuum of space.

Size: Small; HP: 11 (3d6)

Abilities

Stealth (+2)

Sting (+2), 1d4 Edged + 2d4 Special, 1d4 Lingering

Constrict (+1) 2d6 Blunt

Actions - 3

DR

Edged 8 DR

Blunt 4 DR

Firearm 2 DR

Coil Turret

Automated security turret that projects arcing electricity. Safe for use on ships without decompression.

Size: Small; Resilience 20

Abilities

Motion sensing (+1 Perception)

Shock 1d6 Special damage, Range: 9 meters. Successful attacks chain to 1d4 enemies standing within 3 meters of each other 

Generic Human Enemy

More important or particularly powerful enemies or NPCs should be fleshed out as full character sheets, and in that case follow those rules and not creature rules.

Pick an Archetype for the human enemy.

Size: Medium. 3d6 HP with a modifier ranging from 2 to 5.

Abilities (for 4 total)

1 Weapon skill

1-2 Tricks

1-2 Skills

DR

Taken from armor type, determined by archetype.