Some thoughts on the dice used for Thrice RPG

2024-02-14

Here are some thoughts about the dice used in the the Thrice RPG

*Thrice* is an RPG game that recently lauched on Kickstarter. I won’t post the whole Kickstarter detail, but I thought the custom dice are interesting.

A light engine TTRPG with a solid structure, using only d

^{3}s.Thrice Fantasy is a flexible and comprehensive TTRPG, with a fresh and flowing gameplay. The rulebook allows you to play in fantasy settings. Thrice Fantasy is the first product to use the Thrice engine, a rule system that will be employed in various styles and genres, as we’ll explore in upcoming Thrice-based releases.

You can find more detail at the Thrice RPG kickstarter.

Thrice uses special six-sided dice on which the number 1 appears on one face, 2 on two, 3 on three. These dice are d

^{3}, pronounced “d-thrice”. One d-thrice is referred to as 1d^{3}, two dice as 2d^{3}, and so on.Each die rolled in the game aims to obtain a target number, which can be 1, 2 or 3. If the result of a die is equal to the target number, that die scores a success. The target is indicated in round brackets after the number of dice. If a trap inflicts 5d

^{3}(3), the Master rolls 5 dice: each result of 3 represents one damage inflicted.As an alternative to d

^{3}, you can use ordinary six-sided dice (d6). In that case, if the result of a die is equal to or less than the target number, that die scores a success.

This breaks down to:

```
need a 1: 16.6% (1 in 6 chance)
need a 2: 33.3% (1 in 3 chance)
need a 3: 50% (1 in 2 chance)
```

Using a d6 as suggested would be:

```
need a 1: (roll a 1) : 16.6%
need a 2: (roll a 1, 2) : 33.3%
need a 3: (roll a 1, 2, 3): 50%
```

Rolls of 4-6 are ignored. I don’t really like the idea of ignoring dice like this, as the tend to clutter up the dice pools when rolling.

If you want to play around with anydice.com, this formula is for the example given 5d^{3}(3)

`output [count 3 in 5d{1, 2, 2, 3, 3, 3}]`

Chances of each result (counting how many 3s you get):

```
0 "3s": 3.125%
1 "3s": 15.625%
2 "3s": 31.25%
3 "3s": 31.25%
4 "3s": 15.625%
5 "3s": 3.125%
```

The below is a distribution showing 8d^{3}(3). As the rules haven’t been published yet it’s hard to tell how many dice are actually needed during a normal session.

Given that needing a result of (3) is just a 50% distribution this graph makes intuative sense.