Thanks for the feedback! When I say something like STR vs. 3, that's actually you compare your strength score to 3 as if it were another attribute or challenge rating to get your target number. The target numbers will always be 4/8/12/16.
As for the rules on flying creatures, I agree that I should include some sort of rules regarding that. I'm not familiar with the AGE system, so I'll be sure to take a look at that. I also intend to have some kind of chase rules implemented at some point, but they need more time to bake. They're always tricky, and I'm not sure if I want to put them into the grid combat rules or the freeform exploration challenge rules.