Cortex Prime Game Handbook

Taken on it's own, this book is not a great introduction to the Cortex system. This book is a toolkit with a basic set of rules that you add things to until you're happy with your game. The problem is all of the options are thrown at you pretty early on. You do get an example of how dice are rolled and the basics, but then you're thrown in the deep end.

However, at roughly the same time, the publishers of Cortex came out with the play test material for Tales of Xadia and that is a much more focused “book” (something like 50 pages) and a better example of how Cortex can be run. Instead of presenting itself as a ton of options, Tales of Xadia is a specified set of mods that make a cohesive whole. Having that as an example of how a Cortex game can be run really helped things for me. That being said, I think there's some benefit to reading the main book for a little bit, getting confused, and then reading one of the current settings to clarify things (either Hammerheads or Tales of Xadia).

As for the system itself, it's clever. Everything is a die pool of d4s, d6s, d8s, d10s, and d12s. Typically your pool will consist of 3 or more dice. You'll roll them and add two together to get your result. From the remaining dice you can pick one as the effect die where the face doesn't matter, only the size of the die. The bigger the die the greater the result (e.g. a d6 is a middling success, but a d10 is pretty fantastic). From there things expand outwards quickly, but once you've picked your mods, it seems simple enough.

One thing to note for GMs out there is that there is no bestiary, but you don't really need one. By default there's no hit points (there's a mod for that) and since traits are all represented by dice it's easy to make something up or just add dice to the dice pool (in the case of mooks).

I'm looking forward to trying this one out, though it'll likely be with my sons. That being said, I think it'll be easy to adapt for kids and look forward to seeing how they handle it.