A System for Creating Monsters During Play

This page contains my system for creating GURPS monster during play.  The system is pretty simple to use.

Please note: I haven’t uploaded the whole system yet.  Give me time!

Whenever the PCs encounter a monster, just follow these steps:

Step 1: How Many Monsters Are There, and How Tough Are They?

Roll 1d.  (Need a die roller?)

Number of Monsters

Monster Rating by Encounter Difficulty


Trivial Encounter

Standard Encounter

Deadly Encounter

1 N/2 Peril Peril+1 Peril+2
2,3 N Peril-1 Peril Peril+1
4,5 N+N/2 Peril-2 Peril-1 Peril
6 2N Peril-3 Peril-2 Peril-1


  • “N” just means “The number of people in the party.”  Always round up when dividing. 
  • Minimum Peril is 1.  If you need an explanation of Peril Ratings, see here.
Step 2: What Type of Monster Is This?

Roll it up here: What Type of Monster is This?  (I’ve given these tables their own page, because they’re quite extensive)

Step 3: Determine the Stats!

Once you know what type of monster you’re facing, you need to determine its specific stats.

Important note: if you’re playing without a GM, then remember that the basic principle here is that you only determine a monster’s traits when the PCs learn about them – not before! 

Example: you’re facing some sort of demon, and you wonder whether it might be vulnerable to holy water.  Don’t roll to determine whether it’s vulnerable to holy water right away!  Instead, wait until either:

  1. the PCs make a Hidden Lore (Demons) roll, at a penalty equal to Peril, in order to recall this particular type of demon’s weaknesses;
  2. the PCs dump Holy Water on the demon.

Basically, all the monster’s traits are “Schroedinger’s traits” until determined by PC observation.

Q: So where do I find the stats?

Not many are up on the site yet, I’m afraid!  But everntually, I hope to have a whole array of stat tables for each Monster Type listed on the What Type of Monster Is This? pages.

In the meantime – and if you ever need it for edge cases – here’s a generic monster stat block, that can be used to generate monsters appropriate to different Peril Ratings:

The Generic Monster Stat Block

Many, but by no means all, the monsters in this chapter are based on this template. If you need to generate a roughly Peril-appropriate opponent quickly, use this set of stats as a base, and then add a suitable “racial” template on top of it. High-Peril monsters should also have a range of extra attacks, special abilities, and so on!

















DR: (Peril)   (for simplicity, this includes armor)

Relevant Combat Skill:   DX-2+Peril


For strong-but-slow monsters, use 8+(3xPeril) for ST and HP, but subtract one from DX.

For agile-but-weak monsters, use 6+Peril for ST and HP, but add Peril/2 to DX.