I’ve covered this before, but I felt it was a worthy topic to return to. This time, focusing on the GM. As a GM when exactly do you use a Unusual Background? Though I personally found the trait rather intuitive, many GMs seem to be mystified enough to just ignore it – which I think is a mistake. Done right, Unusual Background can add flavor and depth to your campaigns. First, you need to determine everything you’re going to allow into your campaign which is largely determined by what kind of setting your detailing as well as it’s genre. Are you allowing Exotic or Supernatural traits? Which ones? Are their any limitations? Can they only be purchased with a Power Modifier? Are they allowed as “wild” traits? Are certain abilities available, but rare? The Trait Sorter can be useful, but you’ll need to add some of the (few) traits they’ve added since the Basic Set once you’re done with that list. Decide which off-list abilities you’ll allow with a Unusual Background. For example, in a Space Opera game no Exotic or Supernatural trait may be taken without the Psionic Power Modifier or as a part of a Racial Template – but the GM decides that since many of the races in his campaign can interbreed with each other that leveled Unusual Background (Hybrid) trait is available. Each level costs 5 points and allows a character to possess a trait from any racial template other than his own.
The question of rarity is a bit more complicated. How do you, as a GM, determine what is rare in your campaign? The quickest method is to use the 50-10-0 method from GURPS Supers. Is it really rare? As in maybe 200 people on a planet have such capabilities? Then it’s a Unusual Background worth 50 points. Is it uncommon? You can only find people with such capabilities in even the smallest of cities? Then it’s a Unusual Background worth 10 points. Anything more isn’t worth points. Also, if you don’t have GURPS Psionic Campaigns – you should really get it, even if you don’t run games with psionic powers it has a lot of good advice on how to run games with powers in them. The box Unusual Background (Psi) is especially enlightening (see p. 13 of that book). A method which I’ve used in the past uses the Size and Speed/Range Table (p. B550); it’s quite handy! I also like using Eric B. Smith’s Extended Chart.
- Figure the total population of your campaign setting or its referred area. For example, if you’re campaign is set in “modern-day Earth,” then this would be around 7 billion.
- Next, determine the ratio of those with the ability to those without it. For example, if it were literally one in a million, the ratio would be 1:1,000,000
- Next, divide the ratio into the population. In that same example, it would be: 7,000,000,000 / 1,000,000 or 7,000 people worldwide.
- Next, read over the Linear Measurement chart on the Speed/Range Table and then read across to the Speed/Range column, this number is the cost of the Unusual Background to possess that rare capability. Continuing our example, this would be a trait worth 21 points.
- Finally, depending on what exactly the ability is, use the following modifiers to determine the final cost:
- Multiple abilities or access to a entire Power Source (e.g., psionic abilities): round the cost up to the nearest multiple of five.
- Ability is very rare (most people are “latents;” at least 50%) or unknown (there are few, if any countermeasures against it that are available to the public): add 5 to the final cost if one or the other or 10 if both.
- Ability is well known or countermeasures are widely available: divide final cost by 2.Use this modifier after all others; this is incompatible with the unknown modifier (see above).
Example: In the GM’s Scorched Earth campaign, he decides that psionic abilities and beneficial mutations may be possible outside of the Pskyer and Mutate racial templates – but they’ll be pretty rare. After the Storm hit and wiped out most of the population of the planet, only 2,000,000,000 people remain worldwide. The GM decides that 1:400,000 possess either a singular psionic ability or beneficial mutation and. Additionally, countermeasures are widely available since everyone knows about psi powers and biological mutations. Thus possessing either in his campaign is a 10-point Unusual Background.