I haven’t played Mouse Guard or BurningX yet, so this may be inappropriate in situations I have not yet experienced … but …
I’m not a huge fan of dice. Yeah, I grew up with D&D and all the dice that game came with. Lately, I find using dice to lead to arguments about it being “too random” or “unlucky dice”. And if it’s not that, then it’s the “distraction” of people restlessly rolling dice, or throwing dice around in frustration or anger.
At any rate, I’ve started looking at how other games replace dice. And one of the best substitutions has been the use of a regular deck of playing cards.
Method 1: Direct Translation
Use a deck of 49 cards: all 4 suits from Ace to King, removing the 4 Jacks, and add in one Joker.
Any time you “roll a die”, you draw a card instead.
Ace, Two, Three, Four, Five, Six == Failure
Seven, Eight, Nine, Ten, Queen, King == Success
Joker = reshuffle the discards back into the deck and draw again
Queen and King count as “6s” (for cases where rolling a “6” matters)
Some key differences against dice rolls to note: the use of cards add “memory” to the random number generation. Until the deck is reshuffled, having streaks of failures or successes will eventually be balanced back to “normal”. The reason the Joker is in the deck is to discourage players from “counting cards”.
I’d suggest having a separate deck for the GM and the players, especially if there are a lot of players.
Method 2: Explosive Jacks.
Use a deck of 53 cards: all 4 suits from Ace to King, and add in one Joker.
Any time you “roll a die”, you draw a card instead.
Ace = “Critical Failure” : subtract one success, (or count as a success for the opponent)
Jack = “Auspicious Success” : counts as a success, and draw another card (note that you might draw an Ace)
Two, Three, Four, Five, Six == Failure
Seven, Eight, Nine, Ten, Queen, King == Success
Joker = reshuffle the discards back into the deck and draw again
Queen and King count as “6s” (for cases where rolling a “6” matters)
Don’t be misled by the seven success cards vs six failure cards. If I worked out the probability and statistics right, a normal card draw from the full deck results in a 49.8% chance of having (at least 1) success (compared to the 50.0% chance using either Method 1 or the regular die roll).
What I like about explosive jacks is that the number of cards (dice) you use is not a limitation to the number of successes you can get. Normally, if you roll 5 dice, you can only get up to 5 successes (disregarding Fate). With explosive jacks, it is possible to get more without using Fate.