I was immediately sold on Clinton R Nixon’s The Shadow of Yesterday when I read his take on Elves and Goblins.
Elves were once human but have become aloof and immortal. They are reborn again and again but can never die. However, should an elf ever sacrifice their life to save another or should they conceive a child they will fall from elfhood and be reborn one final time.
Goblins on the other hand are twisted creatures that can only find their true form through love.
Wow! This is the stuff of faery tales for sure. Pure gold-dust!
The Shadow of Yesterday also has a pretty awesome game mechanism called Keys that cleverly allow players to focus their efforts on aspects of the game that they enjoy. Keys define the actions for which characters gain experience/advancement e.g. if your character has the key of faith, they would gain one XP for defending their faith to others, two XP for converting someone, and five when they defend their faith, even when it brings great harm upon them.
Cool isn’t it?