3 Dice Mini-games

Gambling is part of many TTRPG tales. It's done with an imaginary currency, so how many players can genuinely say they have never enjoyed a good gamble? My go-to is usually the game I found on Reddit called "Kobold Knuckles" which I've also included an iteration of in D6 Feet Under. It's Blackjack played with d12s, but 11 and 12 count as a 10, and 1 can stand for 1 or 11, to reach 21. Simple, clean, good fun time. Well, lately I've been thinking about mechanics for downtime in my Runehack RPG, and my mind got hung up on the fact that rolling 5+ is twice as likely on a 1d12 than on 1d6. I had to get that out of my head to make space for something that would work way better, which is why I've put this premise into a classic game. Out of that was born another idea, and then one more.

In the end, I got three games of chance that are equally uncertain to the player as they are to the GM.

Shells Game

Three shells, one reward. The reward goes beneath one, and shuffling begins. The player rolls 1d6, or 1d12 if they know how the shells game tricks work. On a roll of 5+, they picked the correct shell and win.

Could it be played with more than three shells? Yes. There's a catch to their numbers though. You'll see later in this article.
Shell Game, by Zeon-in-a-tree

Quite simple, and effective. The chance of succeeding for most is 33%, and it's bumped up to 66% if you know the Shells game. Of course, this could be toyed with beyond the measure depicted. How about we go an extra step?

Monty Hall

Three doors, one reward. The player chooses one door, and the organizer opens one of the doors that do not have a reward. The player now gets a choice - swap to the other unopened door, or stay. Roll a 1d12 if they swapped their choice, or 1d6 if they stayed with their original choice. On a roll of 5+, they picked the correct door and win.

This is the shells game with a twist: You get to change your mind if you dare. It's also a probabilistic expression of the Monty Hall paradox, where switching the door is better than staying with the same door. If you don't believe me, think of it this way - imagine there are 10 doors, and after you pick one, I open 8 doors with no reward behind them. Is it better to switch or not? Of course, it is, the chance that you picked the right door on the first try was and still is 1 in 10.

That got me thinking about something else... could other pairs of regular polyhedral dice accurately represent this for different numbers of shells/doors, assuming there's a single prize every time? (In the case of Monty Hall, assume the organizer opens all but 2 doors.) Let's see!

• 2 doors: coin flip, impossible to open any doors after
• 3 doors: 1d6 on stay, 1d12 on switch, 5+ correct choice
• 4 doors: 1d4 on stay, 1d12 on switch, 4+ correct choice
• 10 doors: 1d10 on stay, 1d100 on switch, 10+ correct choice (treat 00 as zero instead of 100)

... and surprisingly, that's all the dice combinations I could find using regular dice. Maybe I could get Matt Parker on this if I send him a message. Until then, let's see how far we could go with irregular dice and a complete revamp of the game's concept!

Russian Roulette

Start by defining the number of chambers C and the number of bullets B. A player rolls 1dC on the turn (replace C by the current number of chambers), on a roll of B or less they were unlucky. Lower C by 1 after each turn, and lower B by 1 after each unfortunate turn.

Buckshot Roulette has been trending recently. I'm impressed at how they could turn the Russian Roulette into a whole game with actual tactical choices.

I don't know if it can get simpler than this. Highly intuitive, the stakes are clear. One would consider using a deck of cards to be easier, and it is. But... a deck of cards can be shuffled badly, or shuffled in a way to "load" it, keeping the top card the same throughout the whole shuffle. I used to do magic tricks, I know how things can be. Dice make it fair unless they've spent some time in the oven.

The disadvantage of using the dice should be clear by now. For a gun with six chambers, you're going to need 1d6, 1d5, 1d4, 1d3, and 1d2 (1d1 isn't a die, and 1d2 could be a coin). It is easy to do digitally, but not so easy in person. I know some companies sell such dice, but I'm not writing this as a how-to guide. This is just an article where I wanted to write down three ideas for tabletop mini-games to gamble with at the table. Well, four technically, since I described Kobold Knuckles at the top, but let this be the secret kept among everyone who finished reading this article.

That's all for today! I hope to get back to Runehack with my next article, but one never knows when a muse kicks them. Thank you all, and have a wonderful day!