Anyone taken a look at Miasmata ? It's one of the early Greenlight projects on steam.
It's an open world survival game with emphasis on problem solving and exploration rather than combat.
Written by just 2 guys, it's quite an achievement. How the hell they've managed to put so much detail into the world is impressive, must have taken them aaaages.
Here is a 50 minute quicklook CLICKY
It's only £10 on Steam so well worth a look by all accounts.