Handling luck

One of my favorite procedures to use in games is some sort of a “luck roll”, which basically comes up when I want to introduce some amount of uncertainty in a game that doesn’t depend specifically on player actions. (This is distinctly not blorby but sometimes I want to be surprised!)

Existing Rules

Following is a brief survey of some games I’ve played recently that have a mechanic like this.

Call of Cthulhu

In Call of Cthulhu, player characters have a stat called Luck.

Luck rolls may be called for by the Keeper when circumstances external to any investigator are in question, and also when determining the fickle hand of fate. If a skill or characteristic is applicable to a situation then it should be used rather than Luck.

If the Keeper calls for a Group Luck roll, the player whose investigator has the lowest Luck score (among those present in the scene) should make the roll.

If something bad is deemed to happen to one member of the group, the Keeper can simply ask who has the lowest Luck score at that moment and have that individual suffer the unfortunate event.

There’s an optional rule to spend Luck as well, making it a resource to be managed, but that’s a bit different than what I’m discussing here.

Blades in the Dark

Blades in the Dark calls this a Fortune Roll:

The fortune roll is a tool the GM can use to disclaim decision making. You use a fortune roll in two different ways:

When you need to make a determination about a situation the PCs aren’t directly involved in and don’t want to simply decide the outcome.

When an outcome is uncertain, but no other roll applies to the situation at hand.

Roll a d6 (or potentially multiple, using the highest or lowest, depending on circumstances) and interpret it something like this:

• Critical: Exceptional result / Great, extreme effect.
• 6: Good result / Standard,  full effect.
• 4/5: Mixed result / Limited, partial  effect.
• 1-3: Bad result / Poor, little effect.

Into the Odd

My current game engine of choice, Into the Odd, says this:

Sometimes you’ll want an element of randomness without rolling a Save, particularly in situations dictated by luck or those that fall outside of the three Ability Scores. For these situations roll a d6. A high roll favours the Players, and a low roll means bad luck for the Players. The Referee decides what a specific result means for the situation at hand.

Electric Bastionland

Electric Bastionland, the follow-up to Into the Odd, gives a bit more specific guidance around Luck Rolls:

Sometimes you’ll need a roll to represent the element of luck and randomness in the world. The Encounter Roll is an example of this, but you can re-purpose the roll to other uses.

These rolls share a common structure and use a d6.

1	Crisis/Rare: Something that needs addressing immediately, usually bad.
2-3	Warning/Uncommon: A threat or situation that has potential to get serious soon.
4	Normal: The outcome you would expect to be most likely, normally the least threatening.

Adjusting the odds

I personally favor the BitD / ItO approach to luck. One of the interesting things is how much the distribution says about the world. In Blades, the world is against the scoundrels, who have to struggle against mighty odds just to survive. So (assuming just one die), there’s a 1/2 chance of a bad outcome and only a 1/6 chance of something good. Also, the roll is more concrete or dispositive. That is to say, it’s a result: the thing is happening (or has happened) and it’s just a question of whether or not it favors the scoundrels.

But in Electric Bastionland, the world is weird but not necessarily antagonistic towards the treasure hunters. So it’s flipped around: 1/2 a chance that everything is fine and 1/6 that there’s a crisis to address. Even in the worst case, it’s a situation that needs addressing.

Of course, you can tweak this in your game. Maybe each potential outcome has a 1/3 chance. Maybe you change the finality of the consequences. Maybe you turn it into a character stat (I wouldn’t, but you do you).

Regardless, I feel it’s important to set the stakes in advance, before the dice actually hit the table, if you’re going to roll at all. Otherwise, why even roll? If you’re going to have second thoughts when you see that 1 and decide not to present a difficult situation, then perhaps you shouldn’t use these sorts of rolls and instead use your judgment about what should happen. I personally favor this somewhat procedural approach – after all, it’s effectively the same mechanic as used for random encounters in EB, and (taking into consideration character or crew ratings) the same as used for almost everything in Blades.

In fact, to support this approach, EB actually has a set of example luck tables to use in different situations (nightly supply check, using shoddy equipment, ordering “the special”, etc.). This takes it to a somewhat steadier footing, in which this becomes a procedure grounded in the world rather than GM fiat in the moment. These days, that more closely supports my preferred play style.