One of the first things I knew about this design was that the combat system had to be perfect. Any other element could be lackluster, but combat had to be especially Ozzy.
I know what you're thinking: There's no combat in Oz! And my answer is: You're partly right.
If you've only seen the movie, then you don't know how violent the story was. The Tin Woodman wound up using his ax to very good effect in the book. That mainly happened in the first book, with later stories being much more kid-friendly and not very violent at all.
So an Oz combat system should have two basic goals: 1) it should represent fights when they happen and 2) it should be used rarely. I think the final result (which you can download from my website) fills both criteria. It models Oz combats and is scary enough to encourage only minimal use.
The first few things that I noticed were that, in an Oz combat, "size matters" and "limbs go flying." In "The Wonderful Wizard of Oz", the Tin Woodman defeats wolves and bobcats with ease, but even he runs before the sheer bulk of the kalidahs. Which is one of the reasons that Size is a trait in the RPG. I toyed with the idea of having Size equal hit points, until my understanding of the "limbs go flying" principle canceled it out. Then I had Size represent a "saving throw vs. limb loss", until I thought about "dice-flow"; the idea that one person should not make too many die rolls at one time. The current system only worries about relative size.
"Limbs go flying": This one goes back to the Tin Woodman's origin. His ax was enchanted to cut his limbs off one by one. As he lost limbs, he got them replaced with tin, until there was nothing left but tin. Then, in "The Wonderful Wizard of Oz", the Tin Woodman dispatches many of his opponents by beheading them. No generic "damage", just a neat loss of the head. This was continued in Baum's non-Oz story "The Magical Monarch of Mo", which featured a chapter that revolved around the Monarch losing his head in battle with the Purple Dragon and his quest for a replacement.
One of the later items I discovered was "some things just hurt." In "The Land of Oz", General Jinjur's army conquered Oz by poking their opponents with knitting needles. In almost any other system, there would be at least some damage potential to this tactic. 1 hit point at a time, but with enough pokes, a PC could be reduced to a bloody mess just barely hanging on to life. But that was never the idea. The idea was to create a little bit of pain to encourage compliance. And in "Ozma of Oz", Tik-tok clobbers the leader of the Wheelers with a tin dinner pail. Again, this is not intended as a damaging attack. In this case, it's almost like Tik-tok was administering a spanking to the Wheeler (an approved parenting tactic in those days) to encourage him to behave. That's where the concept of Wits damage came in.
"Healing isn't easy" is another lesson I learned from the Tin Woodman. Since no one gets sick in Oz, there are no professional physicians. If you want to recover from your limb loss, you'll have to get creative. The Tin Woodman found a tinsmith to replace his parts. The Magical Monarch of Mo goes through several replacement heads, made of such things as candy and wood, before he is able to get his original head back.
And of course "Not everyone is a fighter." Even though it was Dorothy's dinner pail, it was Tik-tok who swung it.
So to sum up, my design goals were "size matters", "limbs go flying", "some things just hurt", "Healing isn't easy", and "Not everyone is a fighter".
Next week, I'll talk about friends and how important they are in Oz and how that impacted my design.