Benjamin Gauronskas was kind enough to give me a shout-out on his blog Let’s GURPS, saying that he likes the ridiculously large array of adventure-creation tables I posted yesterday. Thanks, Ben!
(Warning: the rest of this post gets pretty technical – fellow GURPSheads only!)
He also makes an interesting point about my choice to use “N” as a measure – he says he would have used CER, instead. This is an intriguing idea. Let’s explore it a little.
First, what are these terms?
“N” is simply a GURPS shorthand for “The number of PCs in the group” (pretty much). It first appeared in Matt Rigsby’s Dungeon Fantasy Adventures 1: Mirror of the Fire Demon. It’s a handy way to make the size of encounters dependent on the size of the PC group. You can say “this encounter will be with N Ogres, or 2N Orcs, or N/2 Giants” – and then the encounter is automatically going to scale up or down in size, depending on the number of PCs. From the perspective of someone writing a procedural system (like I am), that’s really handy!
“CER”, or “Challenge Effectiveness Rating,” was invented by Christopher Rice of Ravens n’ Pennies fame. It first appeared in his article “It’s a Threat!”, in Pyramid #3/77: Combat. It’s a more sophisticated measure than “N,” since it gives you a way to eyeball the overall combat effectiveness of any group of combatants, taking into account their actual capabilities as well as their numbers. I like Christopher Rice’s work a lot, and CER is no exception – it’s a good idea, extremely well executed. Where N measures quantity only, CER manages to measure quality and quantity. This means that CER is a much more precise way to calibrate encounters than N is – though it’s also more complex, and obviously requires more calculation.
So why did I use N rather than CER? Well, there’s the fact that N is really easy to use – by comparison, CER takes a lot of calculation. But that’s not really the main reason. The main reason is that I already had a way to rate encounters by “quality”, as it were: my new system of Peril ratings . (Peril is a bit like B.A.D. from the GURPS Action line, for those who are familiar with it)
In my system, Peril measures quality, and N measures quantity. Splitting them up might seem to make things more complicated (wouldn’t it be simpler to roll them all into one calculation, as in CER?), but it actually makes thing easier for me, since treating them separately means that no complex calculations are necessary: each measure is very simple to use.
Treating Peril as its own thing also makes for some fun, hard choices between risk and reward during the game. Adventures, wilderness journeys, dungeons, monsters etc are rated by Peril – and so are rewards and treasures. The PCs can choose to head into whatever Peril they feel like – they can play it safe, for less chance of decent treasure, or they can head into more dangerous areas in search of greater rewards.
There are also a whole bunch of moments in the system when the Peril gets adjusted whether the players like it or not. For instance, you might arrive at the Forgotten Temple of the Tiger Princess, thinking it’s going to be a cakewalk, only to discover that it’s much more dangerous than you’ve been led to believe. Or you might find that The Crypt of the Deathlord is a lot less dangerous than its name suggests – and if your employer thinks the dangers are greater than they are, and he/she might end up overpaying you. And so on. All of that can be lots of fun!
And that’s why I chose to use N and Peril together, rather than CER.