This is a trove of useful information about the specifics / nuances of Spiral Dice. A must-read, to my mind, if you're at all interested in tinkering with the dice and gaining a better understanding of the why and how they do what they do. It's not a system, though the author / creator has a separate title that provides a rules light robust game called Sapio (also worth checking out). It's also not simply pages of charts with probabilities, though it includes useful graphs to ground the maths involved. A great addition to an already really interesting approach to leveling up your dice for TTRPGs. If that's your jam, I think you'll dig it.