Independent developer BitMonster now offers early access on Steam to GRAV, their sandbox survival game. They note that this project blasted through the Steam Greenlight process in under two days. Here are some screenshots, a gameplay trailer, and more details:

GRAV is an action adventure sandbox survival experience where players explore a multitude of procedurally built planets, build and defend outposts, craft abilities, fight and hunt strange creatures and try to survive while playing either with or against other players in the alien hostile environments. GRAV is a Steam Early Access title and the developers at BitMonster plan to work very closely with the community while we evolve and move GRAV forward!