Hinterland has been out for a little while, but like Eschalon before it, the system I use to determine what goes on Greenhouse next is that:
1. It be great, and
2. that's it.
There's a neat Designer Diary over at RPS that goes into the basic ideas. Hinterland is different every time you play it, cooking you up a custom universe based on your parameters. It's a career of roleplaying thrills compressed into a tight lozenge. The best way I can explain Hinterland is "a RPG/City Construction game with all the dumb parts broken off."
(CW)TB