I thought a mega-thread for this sort of thing would be nice.
http://steamcommunity.com/sharedfiles/fi...d=94505580 Gray Matter (a 2009 Jane Jensen adventure game, with real, human characters and a difficulty curve that's just right)
http://steamcommunity.com/sharedfiles/fi...d=92933628 Ir/rational Investigator (from Tom, the guy who wrote the Penumbra games!)
http://steamcommunity.com/sharedfiles/fi...d=92915716 Miasmata (open-world nature/disease survival game)
http://steamcommunity.com/sharedfiles/fi...d=92922183 Afterfall InSanity (more just to see what it's like though)