For those who are interested in the PDF but would like to offer additional support, we in turn offer the chance to add a piece of your own design to the book. Backers of this tier can propose an NPC with as specific or general features as they wish, which will then be modified for the appropriate setting or mechanical place in the system.
You get to personally work with the designers to develop a world or planar nexus visited by those travelling in this setting. Your development will be acknowledged both in the world's initial description and the credits section.
The only restriction is genre and those races present in the world itself, which must be original or overlap with others included in the rulebook (for reasons of IP law).