There's a lot of interesting talk over at Porky's Expanse regarding the topic of non-rollable dice.
It's turned into a great discussion and you're going to need to read through all the comments to get a greater understanding of what's going on and how we got to the conclusions we've reached, however this is about where we're at: (some of us word each slightly different, but mean the same things.. you really need to read through the comments)
D = character fate, which is the sum of all the following. It's a way to describe the events that happen in a roleplaying game.
D0 = no control or options / impossibility (narrative by the GM)
"You are paralyzed, this is what you see"
"You are in a cage, anything you do provokes a prod from a sharp stick, this is what happens..."
"You have no climbing gear and the wall is smooth obsidian and hard as steel, no you can't climb it."
"It is dark; you are eaten by a grue."
D0.# or D#/#<1 = free will (random vs GM/fate)
"I will turn in for the night, rather than talk to the stranger by the fireplace."
"I decide to not save the villagers."
"I'll take a right at this junction."
"I place the bag of holding in the other bag of holding."
D1 = certainty
"Here is the equipment I want to buy."
"My level 20 ranger doesn't buy provisions and lives off the forest as we travel." ("OK, you don't have to roll for that")
"You travel for two days before you see the castle on the horizon.
"As you approach the castle, this is what you see..."
D1+ = chance (random vs character/person) (D6, D10, D20, etc)
"Roll to see if you hit."
"The monsters rolled D6 damage on you."
"There's a chance this vendor doesn't carry that equipment."
To further things along, we're considering that the negative sign suggests entropy. That is, things nobody has planned for - situations that end up reactive, possibly due to mistakes or the subconscious. If the player makes a mistake, but the GM planned for many outcomes to handle the players, (or perhaps another player planned for) that's a normal situation as described above. If the player makes a mistake that nobody planned for, it would be a -D0.# or -D1
To put it all together:
D = D0 (GM says you come upon a village in distress) + D1/2 (Will players decide to help?) + D1 (purchase normal supplies) + D100 (purchase unusual supplies) -D0.5 (players accidentaly kill only person who knows the way to the dungeon while interrogating them) + D3 (chance to find dungeon) + 3D10 ( chance to survive traps) + 10D6 (battles) + 1D20 (helpful lost adventurer) -2D10 (damage that inflicts player death)
We'd love some more input, so if you think this is something to could get into discussing, by all means, join in. I'd ask comments be left in the main thread at Porky's so we can have a greater discussion. Again, I strongly suggest reading through all the comments to see how we came to these decisions.