Me too I really like Penumbra series. It's a pure indy game made with 2 euros and an immense amount of passion by 2 guy from Sweden, really cool effort and result. Not a perfect game, of course, but with a lot of influence from Looking glass games, IMHO. Their next upcoming game it's really interesting too. This is their dev blog, very interesting ideas e explanation about original gaming in general, highly suggest: http://frictionalgames.blogspot.com/