Fnord
SasqWatch
How about Pathologic?
Haven't tried it myself but it's definitely on my "todo list".
That game is strange. Highly recommended, if you can live with the lousy translation.
I would also recommend The Void & Knock, Knock, by the same developer. Two very different games (and they are also in turn very different compared to Pathologic). Both are very dark though, both in theme & aesthetics, but also quite interesting. I guess both are a bit "love it or hate it" though.
Also, when you get bored of dark & gloomy, you can try their least strange game, Cargo! The Quest for Gravity, where you kick naked dwarves called Buddies, in order to extract fun, which is the only thing that has enough weight to cause gravity, so that you can call down things from the sky which has floated away. Says something about the company when that is their most "normal" game