Design Log Part 1: Core Mechanics

Disclaimer: I have no affiliation with Lab Zero Games and this project is a fan project and is not endorsed by Lab Zero Games or any of its developers and employees.

The following was posted on the Indivisible subreddit. It is copied here for completion of the blog.

Hello everyone. Some of you may have seen my initial ideas of a tabletop roleplaying game based on the world of Indivisible. I am thinking of making an irregular log of my development of the game, both mechanic-wise and lore-wise. Today, I’m starting with the most important part of any RPG: the core mechanics. Do keep in mind that this is nowhere near the final version of the rules, as tweaks will surely follow as the game gets more complex and as I test the rules. Also, the logs assume you know the basics of TTRPGs as I will use some terms quite liberally.

The Core Mechanics

When going into this project, I know straight away I wanted to use the six or seven dice set (that is, a d4 (4-sided die), d6, d8, d10, and d12. Though these sets usually come with d20, I choose to omit it at this juncture as the jump from d12 to d 20 is very large. The reason for the dice set is threefold:

It is quite ubiquitous to many modern RPGs as well as readily available at many game stores, as they are used by Dungeon and Dragons (D&D).

They present an increase in number value without needing to have other numbers to refer to. For example, in D&D, a d20 is always rolled with different modifiers for the rolls in cases of penalties and bonuses. If we’re using the varying die size, and if your Agility is d6, then you roll a d6. Simple. Having said this, there will be cases where the die size will result in an absolute number for some purposes, which I will get to in future posts.

I want to incorporate the number ‘108’ in the game somehow, as it is significant in Buddhism/Hinduism on which the game is based. The number also comes up a few times in the game itself! In this system, a roll of a 10 and an 8 can achieve that 108 nicely. What it actually does is still in the air, though.

I had consulted several RPGs that already use a similar dice size-based system (Ironclaw, Tails of Equestria, Ryuutama being my main ones) and my system is a little different. Without going into how each of those system do it, I want to provide a balanced system where both the Characteristic (e.g. Agility) and the Skill (e.g. Acrobatics) both matter but without one overshadowing the other. I had crunched A LOT of numbers to arrive at the current mechanic that I’m most satisfied with (though it has its flaws).

Player Characteristics

Currently, I decided to go with six Characteristics (or Ability Score) for the game plus one extra as follows:

Physical, Vital, Agility, Intellect, Wisdom, Willpower and Iddhi.

I have not finalise what each of these will contribute to the game, but it’s close to what you would expect. Iddhi is unique to this RPG and can be used to power many different things and I’ll get to that in future posts specifically about Iddhi as it deserves its own whole post.

Skill Tests

To test whether a character succeeds in a given task, say, leap over a large gap in the ground, the character is required to perform a Skill Test. This test is called for by the Game Master, or GM. The GM might ask for an Acrobatics Test, and then ask for a Characteristic to go with it. In this case, they decide to ask for the Agility Characteristic. Let’s say the player has a d6 for their Agility and d8 for their Acrobatics skill. They would roll a d6 and a d8, then add the score together. If the score matches or beat a Target Number (TN) that the GM sets, then they succeed in the task, otherwise they fail. Veteran players of RPG will notice that the GM name the Skill as well as the Characteristic to go with it. I had decided to decouple the Characteristic from Skills as that leaves the GM with more flexibility on what to use in different situations. For example, the Intimidation skill could be used by a show of force (Physical), but also via subtle threats (Intelligence).

The Target Number scales as follow:

4 - Very easy

6 - Easy

8 - Average

10 - Hard

12 - Very Hard

You will notice that this is basically the increasing die size, and after tons of calculations I had found that these numbers scale the best, with standard die roll of the same level (e.g. d8 + d8 vs TN 8) usually succeeding at around 65% of the time, which is similar to many modern RPGs I know.

Well that's it for now! Next time I'll go into using these core mechanics in combat.