Passive Perception

I should probably rename this blog, ‘The Annual Empire’…

That being said, here’s a little idea I had while rereading the Zweihänder rulebook recently.

One of the rules issues that’s bothered me for years is how to run what Zweihänder calls “Secret Tests”. The classic example of this is the test to spot an ambush: it’s the kind of test the player needs to roll, but the very act of rolling tips the player off to what the PC is trying to achieve. Spotting whether an NPC is telling the truth is another example.

Zweihänder has a nice little solution, by having the player roll, but the GM doesn’t reveal the difficulty modifier: the player rolls, the GM describes the result, and in edge cases, at least, the player won’t know how far to trust the GM.

There are, inevitably, weaknesses to this method. It penalises near-successes, for example. But generally, I think it’s a pretty cool way to maintain suspense.

But another way to resolve these issues in a d100 system would be to make more use of the respective digits. I’m a fan of d100 precisely because it can do cool stuff with the various numbers it produces in a single roll (e.g. the d100, the result reversed, the two face digits – other possibilities exist, like the 2d10 sum; the d100 is super-flexible).

So maybe the GM sets a difficulty number from 1-10 to spot an ambush, avoid a guard, detect a lie, or the like, with higher being more difficult. In the case of a roll against an opponent, the base difficulty might be the tens digit of that opponent’s respective skill. So a guard with an awareness of 42 would set a base difficulty of 4, perhaps modified for weather, light, etc.

If the ones digit of the roll exceeds the difficulty number, then things go the roller’s way somehow. A failed roll becomes a “No, but…” result, where the active character doesn’t get what s/he wants, but doesn’t immediately suffer ill effects either. The PC sneaking across the palace garden makes enough noise to attract the attention of a suspicious guard, but not enough to get spotted – the PC ends up trapped in a shrubbery half-way across, waiting for another opportunity. Ambushers are not spotted well in advance, but they don’t get any advantage from surprise either. The PC definitely knows the NPC is lying, but not about what.

If the ones digit exceeds the difficulty but the roll’s a success, then that produces a “Yes, but…” result. The roller achieves what they were trying to do, but a complication resulting from the difficulty arises. The PC sneaks into the palace, but will have to roll again to get out; not all the ambushers benefit from surprise; the NPC lets slip some of the truth but not all of it, or resents the PC for being found out.

This system could be used elsewhere, but I think it’s especially useful when having two sides roll tips the player off. This way, NPCs can ambush the PCs, taking account of the latter’s stats, without having to ask the player to roll.

3 thoughts on “Passive Perception

  1. Fortunately, I’ve never had this problem as I don’t GM round table games. I ran a PBEM for two years which obviously posed no problems for secret dice rolling, and I’m now trying Roll20 which has a ‘GM Roll’ function and I’ve enhanced that by writing a Group Perception macro which switches secrecy ON, makes a perception roll for every character in the group, returns an observation tally, and then switches secrecy OFF. So, I get a neat little list of who see’s something and how much.

  2. Yeah, most of my gaming is done online nowadays, so in practice it isn’t a problem for me either. There’s also the Hitchcock argument that suspense is better than surprise anyway, so tipping off the players that something’s about to happen isn’t necessarily a bad thing, even (or especially!) if the PCs are clueless. Thankfully, the people I play with are excellent at playing to their characters’ knowledge. For me, then, this is a solution without a problem!

  3. True! But there are more atmospheric was of doing this than rattling dice. I don’t know if you’ve ever played Skyrim but anyone who has will remember having to listen carefully to the ambient background noise when creeping through catacombs for the telltale sound of bones knocking together that warned you it was infested with undead.

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