This PDF guide is... exactly what it says it is, but I'm not sure it should be sold by the writers, instead of being given away for free. You are essentially paying for the art and type facing, as the information inside is, while useful, brief. No rules, no extra options, just what is, and what is not compatible from one setting to the other. And honestly, most of that information is pretty common sense. So unless you are looking for more story fluff, or are a GM who owns both games, I can't see this being very useful.

When worlds collide is a short and to the point document. Its all about using numenera materian in The Strange and the other way around. How to use foci from one game in the other. I would say in this way its more about rules conversion than it is about "fluff" or story reason. Which is covered but just slightly. Over all it was a good purchase since I will be using Numenera in my The Strange games.

-Gaming Ronin