Like many of you, I've played a ton of different role playing games. I find it easy to make new stuff up. What I'm learning now is how to make stuff up Numenera Style.
It's all about the KISS: Keep It Simple Stupid. Numenera has simple clean rules. A Numenera adventure should follow suit. Over and over in the editing phase of The Sun Below: City on the Edge, I find myself simplifying. I don't have to create a simulation. I just have to make it fun to play. And fun to GM.
For example, I have a race of blood sucking plant people, the slithik. I have different kinds of slithiks. Do I need so many? No, cut. They all have two attacks a round, one melee, one ranged. Does that make sense? No, cut. The top leader can have two ranged a round, that works.
Sometimes its a matter of making new rules feel Numeneraish. Is that a word? Of course it's a word. Or will be in 1 billion years. :)
I created an artifact where I wanted it to have special effects, but not every time. I could say if you hit with a natural even number, then "tada!" the effect goes off. But that doesn't feel very Numeneraish. What does feel Numeneraish? Ah, if you hit with a natural 17+, then it goes off. Numenera players are already used to cool stuff happening when they roll natural 17s or better.
And so on. Got to get my Numeneraocity on.