I've mentioned Adventurer Conqueror King on this blog before, but I probably did a bad job of describing it. I'll let Tavis Allison tell you what the deal is:
The way the Autarch crew has involved all of its supporters in helping to critique and shape the game is a smart move and will certainly result in a better game. There are already supplements in the works, both from Autarch themselves and from luminaries like Chris Kutalik of the excellent Hill Cantons blog.
I'm happy to be a backer of this project and can't wait to get my hands on the book. (It doesn't hurt that backing it at practically any level gets you cool goodies.)