This system developed out of my attempts to standardise and rationalise the rules for the Dragon Warriors role-playing game for my fantasy campaign. I started out by trying to change the way damage worked and to remove the requirement to follow a particular Profession: however, the more I looked at Dragon Warriors, the more things I found that were unnecessarily complex or applied inconsistently in different circumstances. Over time, I realised that I wanted a substantially different game system, one more like the other game system I use, Champions, while retaining some of the look and feel of Dragon Warriors.
Among other things, I wanted a game system where combat produced potentially fatal outcomes very quickly (unlike Dragon Warriors), where similar tasks used similar game mechanics to determine outcomes (not d100 for some skill checks and d20 for others), and with a range of skill scores greater than four or five points (unlike Champions). I also wanted to use 2d10 to give me a bell curve of values up to 20, unlike the standard 3d6 bell curve or the scattergun outcome of a 1d20 roll. Potestas is the result.
Potestas is a Latin word for the ability, capability or power to do something. I've named my system this because I believe it is a potentially powerful tool in the hands of players and GMs willing to accept and use the overarching core concepts. Although I have provided a number of models for resolving conflicts and contests (such as managing combat), Potestas is not an exhaustive system: you may find the game rules need more fleshing out to cover all possible situations. If your gaming group prefers a strictly defined set of rules, Potestas is unlikely to satisfy your needs.
The game mechanics are intended to be internally consistent between values and in scale: +5 represents the same degree of ability (the same chance of success on a Resolution Roll) no matter what the active value is, and it's always twice as good as +2. There is a substantial degree of abstraction, and of benchmarks chosen for their numerical suitability. For example, characters die at -10 Health because they cannot roll 11 or more on 2d10 with that modifier. Simplicity and mathematical consistency sometimes outweighed accurate modelling of the real world: more accurate swimming and jumping distances are obtained by using a divisor of 5, not 6, and I've done no research to confirm the appropriateness of recovery rates from immediate fatigue. What I hope is that Potestas provides sufficiently realistic results that these adjustments will not affect most players' satisfaction with the game.
There are more things to come, of course: entries in the Bestiary, guidelines for designing new Spells, perhaps an index or more internal links. I'll also put up the scenarios I run using Potestas, along with character designs. Thanks for reading, and thanks for taking a look at my game system!