The Questing Beast

The Questing Beast is an RPG written by James V. West, who also wrote The Pool.

TQB is a great example of modifying a dice mechanic, in this case The Pool's. The difference with The Pool is that TQB has three possible outcomes of a roll, instead of just two. You still need to roll a 1 to be successful. If you don't but roll a 6 then you have failed, otherwise you get a "Guided Event".

When using this system the chance of success remains unchanged, but failure is partially replaced by the "Guided Event". This outcome is a mixed blessing, because the player loses control of what happens, but it's also the only way they can increase their dice pool.

Here's how to get the odds with AnyDice:

function: interpret ROLL:s {
 if (#ROLL)@ROLL = 1 { result: 1 } \ success \
 if 1@ROLL = 6 { result: -1 } \ failure \
 result: 0 \ guided event \
}

loop DICE over {1..10} {
 output [interpret DICE d6] named "[DICE]d"
}

And here it is in a table: