Youkai(basically any type you could possibly give a human appearance, think Touhou maybe if you're familiar with it?) are totally playable. It's just that with skeletons and stuff the in-setting lore is that it's a formless spirit using that kind of body or an undead of some form. I apologize for not having more information on that yet actually posted.

I'll admit this is a personal thing of not feeling like a skeleton "Race" really fits for the setting. ^^;