http://adarkroom.doublespeakgames.com/
Started this yesterday but I have a LOT of time on my hands in my current job so I'd guess I'm a reasonable way in. Pretty simple, but each time I get to a point of thinking 'is that it?' I come across another new area/system to explore/do stuff with.
Easy enough to leave ticking over in the background.
My one suggestion - never bother buying ANYTHING (except Bolases which can be useful) unless you have the most ludicrous stockpile of furs sitting around. You can find/make everything you need easily enough.