X Marks the SpotTLDR When using "x in 6" style checks, decrease the difficulty by decreasing the die size and increase the difficulty by increasing the die size.
Normally I try to flesh out my thoughts to, at minimum, some degree (dubious though those thoughts might be) before posting. However, as part of NaNoWriMo, I’m trying to belt out one post for every day in the month, or try until I start missing death saves, so I just won’t have time to follow my normal process. Instead, I’m going to embrace just letting some thoughts loose as they come to me. We’ll see how it goes.
I run a Lamentations of the Flame Princess (LotFP) play by post game. Built off of the chasis of the B/X version of D&D (with their own added wrinkles), it features a handful of skills with an x chance in 6 style resolution. It’s a lightweight system that works well when you make a straight skill check without modifiers.
Generally, OSR mechanics of this sort tend to be tested flat, that is, without modifiers applied. Consider saving throws. The target number changes with the character level but not with the intensity or difficulty of the actual effect being resisted. A character’s level of expertise or resistance is not influenced by circumstance, good or bad.
Now you can, and people do, modify x in 6 tests but I’ve found the methods a bit clunky and lacking the simplicity of the straight x in 6 but I had a bit of an epiphany when reading through the LotFP book. In the rules for foraging and hunting, I found this tidbit:
Finding enough water to drink is easy in most environments, but in the desert water can only be found if a Bushcraft roll is successfully made on 1d12 rather than 1d6. (bold mine)
Without explicitly laying it out, they’ve introduced an easy way to modify x in 6 tests without overcomplicating things: increase or decrease the size of the die cast for the test depending on the relative difficulty of the task. So if we take the normal x in 6 as the baseline, we can make the test easier by decreasing the die to a 1d4 for an x in 4. Alternatively, we can increase the difficulty of the test by increasing the die to 1d8 (x in 8), 1d10 (x in 10), 1d12 (x in 12), or even 1d20 (x in 20), depending on the difficulty that we’re aiming for.
Breaking down the math a bit, adding a pip to the die result is worth a bit more than reducing the die size. For example, if we begin with a 1 in 6 chance, reducing the test to 1 in 4 generates a 25% chance of success while increasing the pips to 2 in 6 renders a 33% chance of success. This can be leveraged in different ways. We might say that a good set of tools might add a pip to the test. Assistance from an allied (N)PC might decrease the die size. Having help and good tools might do both. Applied to our generic 1 in 6 test, that would result in a 2 in 4 chance, good for a 50% chance, much better than the original 16.6% odds. Working the other way, the ability to increase the die test makes challenging highly skilled specialists easy to calcuulate while still maintaining a simple to reference and apply OSR mechanic.
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