One thing I love to do is create, adapt, or improvise new monsters, creatures, or critters for my players to combat. When you’re just making something up you don’t really need to do anything but what your imagination dictates. But adapting things from mythology or fiction can be a bit harder. How much DR should the dragon have? What sort of air speed should it have? These things can be bothersome, most of the time you should just make a decision and stick with it. There are some good guidelines I like to use.
- If a given critter cannot be hurt by mortal weapons, it probably has DR 24 (4d is typical damage for most handheld melee weapons). It if it’s difficulty, but still possible, give it DR 12.
- If it can’t be hurt be anything give it DR equal to 6 * the number of dice of the most powerful attack in the setting. For example, if the most powerful attack in a campaign is 10d then you should give a creature that cannot be hurt DR 60. Do note that such extreme protection often has limitations on what it protects or gaps in defense. The Bane limitation from GURPS Horror (p. 14) is your go-to trait for this. If it truly cannot be hurt just call it “Invulnerable” and go with that (as suggested by GURPS Powers, p. 118).
- Decide how fast a given critter is by measuring it’s move in something abstract, but quantifiable. For example, can a werewolf out run a human? Then he probably has a Move of 10 or more and is able to outrun most of his prey. Can he move as fast as a fast-moving car (let’s say 40 mph)? That’s probably around a Basic Move of 20 or more then. This works pretty much for all forms of movement.
- How smart is it? Is it bestial, but has a “low cunning” – then it’s probably IQ 6 or 7. Is it as a smart as a man? Then probably IQ 10 or 11. Anything more is getting into the “very smart” range.
- How agile is it? This one should be fairly obvious. If not consider that a DX below 10 is probably outright clumsy, while DX 12 or higher is fairly nimble.
- How strong is it? This one is something that bears a little thought. To low and you won’t present a adequate challenge for combat – too high and it’s gonna be a splatterfest. Like how fast it is, it’s probably best to measure it in a abstract, but quantifiable way. Is it strong as a bear or ox? Can it “kill a man with one blow?” Then it probably has a attack that does at least 3d+1 and up to 17d+1 if it’s a “sure death.” Careful here though, because ST also determines HP (unless you want to change it) and extremely strong beings are also quite capable of taking more damage.
- How tough is it? This is one is always difficult for me. Too high a HT and the critter feels like it’s two or three times more powerful than it is because it just won’t go down. Too low and you get the opposite effect. I like to give most wild animals and similiar beings at least a HT of 11 or more, though if it’s meant to be as tough as a average human then HT 10 works as well. Since HT determines FP, use the same guidelines as above with ST.
- How perceptive is it? Most wild critters should have a modified Perception of 12 or better. Particularly perceptive critters (like wolves) might have a Perception even higher. Again, measure it in a abstract, but quantifiable way.
- How willful is it? Another difficult one. Unless it’s a hive creature never give a Will of less than 10 or 11.
Of course, all of that assumes you are making monsters and not humanoid opponents. When making humanoid foes, use whatever base racial statistics the NPC has and then modify it as follows. Add up each attribute that your player characters and any NPCs that will be used in any combats they have and get the average. Subtract 10, round down, and add that as a bonus to the NPC’s score. For example, if your PCs have ST scores of 14, 11, 9, 17, and 10, Then the average is 12.2. So 12 – 10 = 2. Each NPC then gets a +2 to their racail average attributes. This can be done with skills if need be, but only add up combat-related traits and use their average skill level as the skill level for the NPCs.
Picking Over the Bones
A lot of this requires that you know your player’s characters as well as they do (and really, as a GM, you should). This includes what sort of tactics they like to use, favorite maneuvers, how they approach a battle, and so on. It might be handy to keep a notation of the average “combat ability” of your PCs in case you need to write up a opponent(s) on the fly. Read lots of GURPS material if you can. Compare your statistics to others to see where you stand. Finally, practice practice practice. By working out more and more beasties you’ll get a feel for it. And don’t feel like you can’t modify or redo something you’ve done. I’ve gone back and adjusted things I’ve already used because I knew I’d made a mistake and needed to fix it.